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    Subject[PATCH 13/19] ceph: capability management
    Date
    The Ceph metadata servers control client access to inode metadata and
    file data by issuing capabilities, granting clients permission to read
    and/or write both inode field and file data to OSDs (storage nodes).
    Each capability consists of a set of bits indicating which operations
    are allowed.

    If the client holds a *_SHARED cap, the client has a coherent value
    that can be safely read from the cached inode.

    In the case of a *_EXCL (exclusive) or FILE_WR capabilities, the client
    is allowed to change inode attributes (e.g., file size, mtime), note
    its dirty state in the ceph_cap, and asynchronously flush that
    metadata change to the MDS.

    In the event of a conflicting operation (perhaps by another client),
    the MDS will revoke the conflicting client capabilities.

    In order for a client to cache an inode, it must hold a capability
    with at least one MDS server. When inodes are released, release
    notifications are batched and periodically sent en masse to the MDS
    cluster to release server state.

    Signed-off-by: Sage Weil <sage@newdream.net>
    ---
    fs/ceph/caps.c | 2785 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
    1 files changed, 2785 insertions(+), 0 deletions(-)
    create mode 100644 fs/ceph/caps.c

    diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
    new file mode 100644
    index 0000000..cf964a9
    --- /dev/null
    +++ b/fs/ceph/caps.c
    @@ -0,0 +1,2785 @@
    +#include <linux/fs.h>
    +#include <linux/kernel.h>
    +#include <linux/sched.h>
    +#include <linux/wait.h>
    +
    +#include "ceph_debug.h"
    +#include "super.h"
    +#include "decode.h"
    +#include "messenger.h"
    +
    +/*
    + * Capability management
    + *
    + * The Ceph metadata servers control client access to inode metadata
    + * and file data by issuing capabilities, granting clients permission
    + * to read and/or write both inode field and file data to OSDs
    + * (storage nodes). Each capability consists of a set of bits
    + * indicating which operations are allowed.
    + *
    + * If the client holds a *_SHARED cap, the client has a coherent value
    + * that can be safely read from the cached inode.
    + *
    + * In the case of a *_EXCL (exclusive) or FILE_WR capabilities, the
    + * client is allowed to change inode attributes (e.g., file size,
    + * mtime), note its dirty state in the ceph_cap, and asynchronously
    + * flush that metadata change to the MDS.
    + *
    + * In the event of a conflicting operation (perhaps by another
    + * client), the MDS will revoke the conflicting client capabilities.
    + *
    + * In order for a client to cache an inode, it must hold a capability
    + * with at least one MDS server. When inodes are released, release
    + * notifications are batched and periodically sent en masse to the MDS
    + * cluster to release server state.
    + */
    +
    +
    +/*
    + * Generate readable cap strings for debugging output.
    + */
    +#define MAX_CAP_STR 20
    +static char cap_str[MAX_CAP_STR][40];
    +static DEFINE_SPINLOCK(cap_str_lock);
    +static int last_cap_str;
    +
    +static char *gcap_string(char *s, int c)
    +{
    + if (c & CEPH_CAP_GSHARED)
    + *s++ = 's';
    + if (c & CEPH_CAP_GEXCL)
    + *s++ = 'x';
    + if (c & CEPH_CAP_GCACHE)
    + *s++ = 'c';
    + if (c & CEPH_CAP_GRD)
    + *s++ = 'r';
    + if (c & CEPH_CAP_GWR)
    + *s++ = 'w';
    + if (c & CEPH_CAP_GBUFFER)
    + *s++ = 'b';
    + if (c & CEPH_CAP_GLAZYIO)
    + *s++ = 'l';
    + return s;
    +}
    +
    +const char *ceph_cap_string(int caps)
    +{
    + int i;
    + char *s;
    + int c;
    +
    + spin_lock(&cap_str_lock);
    + i = last_cap_str++;
    + if (last_cap_str == MAX_CAP_STR)
    + last_cap_str = 0;
    + spin_unlock(&cap_str_lock);
    +
    + s = cap_str[i];
    +
    + if (caps & CEPH_CAP_PIN)
    + *s++ = 'p';
    +
    + c = (caps >> CEPH_CAP_SAUTH) & 3;
    + if (c) {
    + *s++ = 'A';
    + s = gcap_string(s, c);
    + }
    +
    + c = (caps >> CEPH_CAP_SLINK) & 3;
    + if (c) {
    + *s++ = 'L';
    + s = gcap_string(s, c);
    + }
    +
    + c = (caps >> CEPH_CAP_SXATTR) & 3;
    + if (c) {
    + *s++ = 'X';
    + s = gcap_string(s, c);
    + }
    +
    + c = caps >> CEPH_CAP_SFILE;
    + if (c) {
    + *s++ = 'F';
    + s = gcap_string(s, c);
    + }
    +
    + if (s == cap_str[i])
    + *s++ = '-';
    + *s = 0;
    + return cap_str[i];
    +}
    +
    +/*
    + * Cap reservations
    + *
    + * Maintain a global pool of preallocated struct ceph_caps, referenced
    + * by struct ceph_caps_reservations. This ensures that we preallocate
    + * memory needed to successfully process an MDS response. (If an MDS
    + * sends us cap information and we fail to process it, we will have
    + * problems due to the client and MDS being out of sync.)
    + *
    + * Reservations are 'owned' by a ceph_cap_reservation context.
    + */
    +static spinlock_t caps_list_lock;
    +static struct list_head caps_list; /* unused (reserved or unreserved) */
    +static int caps_total_count; /* total caps allocated */
    +static int caps_use_count; /* in use */
    +static int caps_reserve_count; /* unused, reserved */
    +static int caps_avail_count; /* unused, unreserved */
    +
    +void ceph_caps_init(void)
    +{
    + INIT_LIST_HEAD(&caps_list);
    + spin_lock_init(&caps_list_lock);
    +}
    +
    +void ceph_caps_finalize(void)
    +{
    + struct ceph_cap *cap;
    +
    + spin_lock(&caps_list_lock);
    + while (!list_empty(&caps_list)) {
    + cap = list_first_entry(&caps_list, struct ceph_cap, caps_item);
    + list_del(&cap->caps_item);
    + kmem_cache_free(ceph_cap_cachep, cap);
    + }
    + caps_total_count = 0;
    + caps_avail_count = 0;
    + caps_use_count = 0;
    + caps_reserve_count = 0;
    + spin_unlock(&caps_list_lock);
    +}
    +
    +int ceph_reserve_caps(struct ceph_cap_reservation *ctx, int need)
    +{
    + int i;
    + struct ceph_cap *cap;
    + int have;
    + int alloc = 0;
    + LIST_HEAD(newcaps);
    + int ret = 0;
    +
    + dout("reserve caps ctx=%p need=%d\n", ctx, need);
    +
    + /* first reserve any caps that are already allocated */
    + spin_lock(&caps_list_lock);
    + if (caps_avail_count >= need)
    + have = need;
    + else
    + have = caps_avail_count;
    + caps_avail_count -= have;
    + caps_reserve_count += have;
    + BUG_ON(caps_total_count != caps_use_count + caps_reserve_count +
    + caps_avail_count);
    + spin_unlock(&caps_list_lock);
    +
    + for (i = have; i < need; i++) {
    + cap = kmem_cache_alloc(ceph_cap_cachep, GFP_NOFS);
    + if (!cap) {
    + ret = -ENOMEM;
    + goto out_alloc_count;
    + }
    + list_add(&cap->caps_item, &newcaps);
    + alloc++;
    + }
    + BUG_ON(have + alloc != need);
    +
    + spin_lock(&caps_list_lock);
    + caps_total_count += alloc;
    + caps_reserve_count += alloc;
    + list_splice(&newcaps, &caps_list);
    +
    + BUG_ON(caps_total_count != caps_use_count + caps_reserve_count +
    + caps_avail_count);
    + spin_unlock(&caps_list_lock);
    +
    + ctx->count = need;
    + dout("reserve caps ctx=%p %d = %d used + %d resv + %d avail\n",
    + ctx, caps_total_count, caps_use_count, caps_reserve_count,
    + caps_avail_count);
    + return 0;
    +
    +out_alloc_count:
    + /* we didn't manage to reserve as much as we needed */
    + pr_warning("ceph reserve caps ctx=%p ENOMEM need=%d got=%d\n",
    + ctx, need, have);
    + return ret;
    +}
    +
    +int ceph_unreserve_caps(struct ceph_cap_reservation *ctx)
    +{
    + dout("unreserve caps ctx=%p count=%d\n", ctx, ctx->count);
    + if (ctx->count) {
    + spin_lock(&caps_list_lock);
    + BUG_ON(caps_reserve_count < ctx->count);
    + caps_reserve_count -= ctx->count;
    + caps_avail_count += ctx->count;
    + ctx->count = 0;
    + dout("unreserve caps %d = %d used + %d resv + %d avail\n",
    + caps_total_count, caps_use_count, caps_reserve_count,
    + caps_avail_count);
    + BUG_ON(caps_total_count != caps_use_count + caps_reserve_count +
    + caps_avail_count);
    + spin_unlock(&caps_list_lock);
    + }
    + return 0;
    +}
    +
    +static struct ceph_cap *get_cap(struct ceph_cap_reservation *ctx)
    +{
    + struct ceph_cap *cap = NULL;
    +
    + /* temporary, until we do something about cap import/export */
    + if (!ctx)
    + return kmem_cache_alloc(ceph_cap_cachep, GFP_NOFS);
    +
    + spin_lock(&caps_list_lock);
    + dout("get_cap ctx=%p (%d) %d = %d used + %d resv + %d avail\n",
    + ctx, ctx->count, caps_total_count, caps_use_count,
    + caps_reserve_count, caps_avail_count);
    + BUG_ON(!ctx->count);
    + BUG_ON(ctx->count > caps_reserve_count);
    + BUG_ON(list_empty(&caps_list));
    +
    + ctx->count--;
    + caps_reserve_count--;
    + caps_use_count++;
    +
    + cap = list_first_entry(&caps_list, struct ceph_cap, caps_item);
    + list_del(&cap->caps_item);
    +
    + BUG_ON(caps_total_count != caps_use_count + caps_reserve_count +
    + caps_avail_count);
    + spin_unlock(&caps_list_lock);
    + return cap;
    +}
    +
    +static void put_cap(struct ceph_cap *cap,
    + struct ceph_cap_reservation *ctx)
    +{
    + spin_lock(&caps_list_lock);
    + dout("put_cap ctx=%p (%d) %d = %d used + %d resv + %d avail\n",
    + ctx, ctx ? ctx->count : 0, caps_total_count, caps_use_count,
    + caps_reserve_count, caps_avail_count);
    + caps_use_count--;
    + /*
    + * Keep some preallocated caps around, at least enough to do a
    + * readdir (which needs to preallocate lots of them), to avoid
    + * lots of free/alloc churn.
    + */
    + if (caps_avail_count >= caps_reserve_count +
    + ceph_client(cap->ci->vfs_inode.i_sb)->mount_args.max_readdir) {
    + caps_total_count--;
    + kfree(cap);
    + } else {
    + if (ctx) {
    + ctx->count++;
    + caps_reserve_count++;
    + } else {
    + caps_avail_count++;
    + }
    + list_add(&cap->caps_item, &caps_list);
    + }
    +
    + BUG_ON(caps_total_count != caps_use_count + caps_reserve_count +
    + caps_avail_count);
    + spin_unlock(&caps_list_lock);
    +}
    +
    +void ceph_reservation_status(int *total, int *avail, int *used, int *reserved)
    +{
    + if (total)
    + *total = caps_total_count;
    + if (avail)
    + *avail = caps_avail_count;
    + if (used)
    + *used = caps_use_count;
    + if (reserved)
    + *reserved = caps_reserve_count;
    +}
    +
    +/*
    + * Find ceph_cap for given mds, if any.
    + *
    + * Called with i_lock held.
    + */
    +static struct ceph_cap *__get_cap_for_mds(struct ceph_inode_info *ci, int mds)
    +{
    + struct ceph_cap *cap;
    + struct rb_node *n = ci->i_caps.rb_node;
    +
    + while (n) {
    + cap = rb_entry(n, struct ceph_cap, ci_node);
    + if (mds < cap->mds)
    + n = n->rb_left;
    + else if (mds > cap->mds)
    + n = n->rb_right;
    + else
    + return cap;
    + }
    + return NULL;
    +}
    +
    +/*
    + * Return id of any MDS with a cap, preferably FILE_WR|WRBUFFER|EXCL, else
    + * -1.
    + */
    +static int __ceph_get_cap_mds(struct ceph_inode_info *ci, u32 *mseq)
    +{
    + struct ceph_cap *cap;
    + int mds = -1;
    + struct rb_node *p;
    +
    + /* prefer mds with WR|WRBUFFER|EXCL caps */
    + for (p = rb_first(&ci->i_caps); p; p = rb_next(p)) {
    + cap = rb_entry(p, struct ceph_cap, ci_node);
    + mds = cap->mds;
    + if (mseq)
    + *mseq = cap->mseq;
    + if (cap->issued & (CEPH_CAP_FILE_WR |
    + CEPH_CAP_FILE_BUFFER |
    + CEPH_CAP_FILE_EXCL))
    + break;
    + }
    + return mds;
    +}
    +
    +int ceph_get_cap_mds(struct inode *inode)
    +{
    + int mds;
    + spin_lock(&inode->i_lock);
    + mds = __ceph_get_cap_mds(ceph_inode(inode), NULL);
    + spin_unlock(&inode->i_lock);
    + return mds;
    +}
    +
    +/*
    + * Called under i_lock.
    + */
    +static void __insert_cap_node(struct ceph_inode_info *ci,
    + struct ceph_cap *new)
    +{
    + struct rb_node **p = &ci->i_caps.rb_node;
    + struct rb_node *parent = NULL;
    + struct ceph_cap *cap = NULL;
    +
    + while (*p) {
    + parent = *p;
    + cap = rb_entry(parent, struct ceph_cap, ci_node);
    + if (new->mds < cap->mds)
    + p = &(*p)->rb_left;
    + else if (new->mds > cap->mds)
    + p = &(*p)->rb_right;
    + else
    + BUG();
    + }
    +
    + rb_link_node(&new->ci_node, parent, p);
    + rb_insert_color(&new->ci_node, &ci->i_caps);
    +}
    +
    +/*
    + * (re)set cap hold timeouts, which control the delayed release
    + * of unused caps back to the MDS. Should be called on cap use.
    + */
    +static void __cap_set_timeouts(struct ceph_mds_client *mdsc,
    + struct ceph_inode_info *ci)
    +{
    + struct ceph_mount_args *ma = &mdsc->client->mount_args;
    +
    + ci->i_hold_caps_min = round_jiffies(jiffies +
    + ma->caps_wanted_delay_min * HZ);
    + ci->i_hold_caps_max = round_jiffies(jiffies +
    + ma->caps_wanted_delay_max * HZ);
    + dout("__cap_set_timeouts %p min %lu max %lu\n", &ci->vfs_inode,
    + ci->i_hold_caps_min - jiffies, ci->i_hold_caps_max - jiffies);
    +}
    +
    +/*
    + * (Re)queue cap at the end of the delayed cap release list.
    + *
    + * If I_FLUSH is set, leave the inode at the front of the list.
    + *
    + * Caller holds i_lock
    + * -> we take mdsc->cap_delay_lock
    + */
    +static void __cap_delay_requeue(struct ceph_mds_client *mdsc,
    + struct ceph_inode_info *ci)
    +{
    + __cap_set_timeouts(mdsc, ci);
    + dout("__cap_delay_requeue %p flags %d at %lu\n", &ci->vfs_inode,
    + ci->i_ceph_flags, ci->i_hold_caps_max);
    + if (!mdsc->stopping) {
    + spin_lock(&mdsc->cap_delay_lock);
    + if (!list_empty(&ci->i_cap_delay_list)) {
    + if (ci->i_ceph_flags & CEPH_I_FLUSH)
    + goto no_change;
    + list_del_init(&ci->i_cap_delay_list);
    + }
    + list_add_tail(&ci->i_cap_delay_list, &mdsc->cap_delay_list);
    + no_change:
    + spin_unlock(&mdsc->cap_delay_lock);
    + }
    +}
    +
    +/*
    + * Queue an inode for immediate writeback. Mark inode with I_FLUSH,
    + * indicating we should send a cap message to flush dirty metadata
    + * asap, and move to the front of the delayed cap list.
    + */
    +static void __cap_delay_requeue_front(struct ceph_mds_client *mdsc,
    + struct ceph_inode_info *ci)
    +{
    + dout("__cap_delay_requeue_front %p\n", &ci->vfs_inode);
    + spin_lock(&mdsc->cap_delay_lock);
    + ci->i_ceph_flags |= CEPH_I_FLUSH;
    + if (!list_empty(&ci->i_cap_delay_list))
    + list_del_init(&ci->i_cap_delay_list);
    + list_add(&ci->i_cap_delay_list, &mdsc->cap_delay_list);
    + spin_unlock(&mdsc->cap_delay_lock);
    +}
    +
    +/*
    + * Cancel delayed work on cap.
    + *
    + * Caller must hold i_lock.
    + */
    +static void __cap_delay_cancel(struct ceph_mds_client *mdsc,
    + struct ceph_inode_info *ci)
    +{
    + dout("__cap_delay_cancel %p\n", &ci->vfs_inode);
    + if (list_empty(&ci->i_cap_delay_list))
    + return;
    + spin_lock(&mdsc->cap_delay_lock);
    + list_del_init(&ci->i_cap_delay_list);
    + spin_unlock(&mdsc->cap_delay_lock);
    +}
    +
    +/*
    + * Add a capability under the given MDS session.
    + *
    + * Caller should hold session snap_rwsem (read) and s_mutex.
    + *
    + * @fmode is the open file mode, if we are opening a file, otherwise
    + * it is < 0. (This is so we can atomically add the cap and add an
    + * open file reference to it.)
    + */
    +int ceph_add_cap(struct inode *inode,
    + struct ceph_mds_session *session, u64 cap_id,
    + int fmode, unsigned issued, unsigned wanted,
    + unsigned seq, unsigned mseq, u64 realmino,
    + unsigned ttl_ms, unsigned long ttl_from, int flags,
    + struct ceph_cap_reservation *caps_reservation)
    +{
    + struct ceph_mds_client *mdsc = &ceph_inode_to_client(inode)->mdsc;
    + struct ceph_inode_info *ci = ceph_inode(inode);
    + struct ceph_cap *new_cap = NULL;
    + struct ceph_cap *cap;
    + int mds = session->s_mds;
    + int actual_wanted;
    +
    + dout("add_cap %p mds%d cap %llx %s seq %d\n", inode,
    + session->s_mds, cap_id, ceph_cap_string(issued), seq);
    +
    + /*
    + * If we are opening the file, include file mode wanted bits
    + * in wanted.
    + */
    + if (fmode >= 0)
    + wanted |= ceph_caps_for_mode(fmode);
    +
    +retry:
    + spin_lock(&inode->i_lock);
    + cap = __get_cap_for_mds(ci, mds);
    + if (!cap) {
    + if (new_cap) {
    + cap = new_cap;
    + new_cap = NULL;
    + } else {
    + spin_unlock(&inode->i_lock);
    + new_cap = get_cap(caps_reservation);
    + if (new_cap == NULL)
    + return -ENOMEM;
    + goto retry;
    + }
    +
    + cap->issued = 0;
    + cap->implemented = 0;
    + cap->mds = mds;
    + cap->mds_wanted = 0;
    +
    + cap->ci = ci;
    + __insert_cap_node(ci, cap);
    +
    + /* clear out old exporting info? (i.e. on cap import) */
    + if (ci->i_cap_exporting_mds == mds) {
    + ci->i_cap_exporting_issued = 0;
    + ci->i_cap_exporting_mseq = 0;
    + ci->i_cap_exporting_mds = -1;
    + }
    +
    + /* add to session cap list */
    + cap->session = session;
    + spin_lock(&session->s_cap_lock);
    + list_add_tail(&cap->session_caps, &session->s_caps);
    + session->s_nr_caps++;
    + spin_unlock(&session->s_cap_lock);
    + }
    +
    + if (!ci->i_snap_realm) {
    + /*
    + * add this inode to the appropriate snap realm
    + */
    + struct ceph_snap_realm *realm = ceph_lookup_snap_realm(mdsc,
    + realmino);
    + if (realm) {
    + ceph_get_snap_realm(mdsc, realm);
    + spin_lock(&realm->inodes_with_caps_lock);
    + ci->i_snap_realm = realm;
    + list_add(&ci->i_snap_realm_item,
    + &realm->inodes_with_caps);
    + spin_unlock(&realm->inodes_with_caps_lock);
    + } else {
    + pr_err("ceph_add_cap: couldn't find snap realm %llu\n",
    + realmino);
    + }
    + }
    +
    + /*
    + * if we are newly issued FILE_SHARED, clear I_COMPLETE; we
    + * don't know what happened to this directory while we didn't
    + * have the cap.
    + */
    + if (S_ISDIR(inode->i_mode) &&
    + (issued & CEPH_CAP_FILE_SHARED) &&
    + (cap->issued & CEPH_CAP_FILE_SHARED) == 0) {
    + dout(" marking %p NOT complete\n", inode);
    + ci->i_ceph_flags &= ~CEPH_I_COMPLETE;
    + }
    +
    + /*
    + * If we are issued caps we don't want, or the mds' wanted
    + * value appears to be off, queue a check so we'll release
    + * later and/or update the mds wanted value.
    + */
    + actual_wanted = __ceph_caps_wanted(ci);
    + if ((wanted & ~actual_wanted) ||
    + (issued & ~actual_wanted & CEPH_CAP_ANY_WR)) {
    + dout(" issued %s, mds wanted %s, actual %s, queueing\n",
    + ceph_cap_string(issued), ceph_cap_string(wanted),
    + ceph_cap_string(actual_wanted));
    + __cap_delay_requeue(mdsc, ci);
    + }
    +
    + if (flags & CEPH_CAP_FLAG_AUTH)
    + ci->i_auth_cap = cap;
    + else if (ci->i_auth_cap == cap)
    + ci->i_auth_cap = NULL;
    +
    + dout("add_cap inode %p (%llx.%llx) cap %p %s now %s seq %d mds%d\n",
    + inode, ceph_vinop(inode), cap, ceph_cap_string(issued),
    + ceph_cap_string(issued|cap->issued), seq, mds);
    + cap->cap_id = cap_id;
    + cap->issued = issued;
    + cap->implemented |= issued;
    + cap->mds_wanted |= wanted;
    + cap->seq = seq;
    + cap->issue_seq = seq;
    + cap->mseq = mseq;
    + cap->gen = session->s_cap_gen;
    +
    + if (fmode >= 0)
    + __ceph_get_fmode(ci, fmode);
    + spin_unlock(&inode->i_lock);
    + wake_up(&ci->i_cap_wq);
    + return 0;
    +}
    +
    +/*
    + * Return true if cap has not timed out and belongs to the current
    + * generation of the MDS session (i.e. has not gone 'stale' due to
    + * us losing touch with the mds).
    + */
    +static int __cap_is_valid(struct ceph_cap *cap)
    +{
    + unsigned long ttl;
    + u32 gen;
    +
    + spin_lock(&cap->session->s_cap_lock);
    + gen = cap->session->s_cap_gen;
    + ttl = cap->session->s_cap_ttl;
    + spin_unlock(&cap->session->s_cap_lock);
    +
    + if (cap->gen < gen || time_after_eq(jiffies, ttl)) {
    + dout("__cap_is_valid %p cap %p issued %s "
    + "but STALE (gen %u vs %u)\n", &cap->ci->vfs_inode,
    + cap, ceph_cap_string(cap->issued), cap->gen, gen);
    + return 0;
    + }
    +
    + return 1;
    +}
    +
    +/*
    + * Return set of valid cap bits issued to us. Note that caps time
    + * out, and may be invalidated in bulk if the client session times out
    + * and session->s_cap_gen is bumped.
    + */
    +int __ceph_caps_issued(struct ceph_inode_info *ci, int *implemented)
    +{
    + int have = ci->i_snap_caps;
    + struct ceph_cap *cap;
    + struct rb_node *p;
    +
    + if (implemented)
    + *implemented = 0;
    + for (p = rb_first(&ci->i_caps); p; p = rb_next(p)) {
    + cap = rb_entry(p, struct ceph_cap, ci_node);
    + if (!__cap_is_valid(cap))
    + continue;
    + dout("__ceph_caps_issued %p cap %p issued %s\n",
    + &ci->vfs_inode, cap, ceph_cap_string(cap->issued));
    + have |= cap->issued;
    + if (implemented)
    + *implemented |= cap->implemented;
    + }
    + return have;
    +}
    +
    +/*
    + * Get cap bits issued by caps other than @ocap
    + */
    +int __ceph_caps_issued_other(struct ceph_inode_info *ci, struct ceph_cap *ocap)
    +{
    + int have = ci->i_snap_caps;
    + struct ceph_cap *cap;
    + struct rb_node *p;
    +
    + for (p = rb_first(&ci->i_caps); p; p = rb_next(p)) {
    + cap = rb_entry(p, struct ceph_cap, ci_node);
    + if (cap == ocap)
    + continue;
    + if (!__cap_is_valid(cap))
    + continue;
    + have |= cap->issued;
    + }
    + return have;
    +}
    +
    +/*
    + * Move a cap to the end of the LRU (oldest caps at list head, newest
    + * at list tail).
    + */
    +static void __touch_cap(struct ceph_cap *cap)
    +{
    + struct ceph_mds_session *s = cap->session;
    +
    + dout("__touch_cap %p cap %p mds%d\n", &cap->ci->vfs_inode, cap,
    + s->s_mds);
    + spin_lock(&s->s_cap_lock);
    + list_move_tail(&cap->session_caps, &s->s_caps);
    + spin_unlock(&s->s_cap_lock);
    +}
    +
    +/*
    + * Check if we hold the given mask. If so, move the cap(s) to the
    + * front of their respective LRUs. (This is the preferred way for
    + * callers to check for caps they want.)
    + */
    +int __ceph_caps_issued_mask(struct ceph_inode_info *ci, int mask, int touch)
    +{
    + struct ceph_cap *cap;
    + struct rb_node *p;
    + int have = ci->i_snap_caps;
    +
    + if ((have & mask) == mask) {
    + dout("__ceph_caps_issued_mask %p snap issued %s"
    + " (mask %s)\n", &ci->vfs_inode,
    + ceph_cap_string(have),
    + ceph_cap_string(mask));
    + return 1;
    + }
    +
    + for (p = rb_first(&ci->i_caps); p; p = rb_next(p)) {
    + cap = rb_entry(p, struct ceph_cap, ci_node);
    + if (!__cap_is_valid(cap))
    + continue;
    + if ((cap->issued & mask) == mask) {
    + dout("__ceph_caps_issued_mask %p cap %p issued %s"
    + " (mask %s)\n", &ci->vfs_inode, cap,
    + ceph_cap_string(cap->issued),
    + ceph_cap_string(mask));
    + if (touch)
    + __touch_cap(cap);
    + return 1;
    + }
    +
    + /* does a combination of caps satisfy mask? */
    + have |= cap->issued;
    + if ((have & mask) == mask) {
    + dout("__ceph_caps_issued_mask %p combo issued %s"
    + " (mask %s)\n", &ci->vfs_inode,
    + ceph_cap_string(cap->issued),
    + ceph_cap_string(mask));
    + if (touch) {
    + struct rb_node *q;
    +
    + /* touch this + preceeding caps */
    + __touch_cap(cap);
    + for (q = rb_first(&ci->i_caps); q != p;
    + q = rb_next(q)) {
    + cap = rb_entry(q, struct ceph_cap,
    + ci_node);
    + if (!__cap_is_valid(cap))
    + continue;
    + __touch_cap(cap);
    + }
    + }
    + return 1;
    + }
    + }
    +
    + return 0;
    +}
    +
    +/*
    + * Return true if mask caps are currently being revoked by an MDS.
    + */
    +int ceph_caps_revoking(struct ceph_inode_info *ci, int mask)
    +{
    + struct inode *inode = &ci->vfs_inode;
    + struct ceph_cap *cap;
    + struct rb_node *p;
    + int ret = 0;
    +
    + spin_lock(&inode->i_lock);
    + for (p = rb_first(&ci->i_caps); p; p = rb_next(p)) {
    + cap = rb_entry(p, struct ceph_cap, ci_node);
    + if (__cap_is_valid(cap) &&
    + (cap->implemented & ~cap->issued & mask)) {
    + ret = 1;
    + break;
    + }
    + }
    + spin_unlock(&inode->i_lock);
    + dout("ceph_caps_revoking %p %s = %d\n", inode,
    + ceph_cap_string(mask), ret);
    + return ret;
    +}
    +
    +/*
    + * Return caps we have registered with the MDS(s) as 'wanted'.
    + */
    +int __ceph_caps_mds_wanted(struct ceph_inode_info *ci)
    +{
    + struct ceph_cap *cap;
    + struct rb_node *p;
    + int mds_wanted = 0;
    +
    + for (p = rb_first(&ci->i_caps); p; p = rb_next(p)) {
    + cap = rb_entry(p, struct ceph_cap, ci_node);
    + if (!__cap_is_valid(cap))
    + continue;
    + mds_wanted |= cap->mds_wanted;
    + }
    + return mds_wanted;
    +}
    +
    +/*
    + * called under i_lock
    + */
    +static int __ceph_is_any_caps(struct ceph_inode_info *ci)
    +{
    + return !RB_EMPTY_ROOT(&ci->i_caps) || ci->i_cap_exporting_mds >= 0;
    +}
    +
    +/*
    + * caller should hold i_lock, and session s_mutex.
    + * returns true if this is the last cap. if so, caller should iput.
    + */
    +void __ceph_remove_cap(struct ceph_cap *cap,
    + struct ceph_cap_reservation *ctx)
    +{
    + struct ceph_mds_session *session = cap->session;
    + struct ceph_inode_info *ci = cap->ci;
    + struct ceph_mds_client *mdsc = &ceph_client(ci->vfs_inode.i_sb)->mdsc;
    +
    + dout("__ceph_remove_cap %p from %p\n", cap, &ci->vfs_inode);
    +
    + /* remove from session list */
    + spin_lock(&session->s_cap_lock);
    + list_del_init(&cap->session_caps);
    + session->s_nr_caps--;
    + spin_unlock(&session->s_cap_lock);
    +
    + /* remove from inode list */
    + rb_erase(&cap->ci_node, &ci->i_caps);
    + cap->session = NULL;
    + if (ci->i_auth_cap == cap)
    + ci->i_auth_cap = NULL;
    +
    + put_cap(cap, ctx);
    +
    + if (!__ceph_is_any_caps(ci)) {
    + struct ceph_snap_realm *realm = ci->i_snap_realm;
    + spin_lock(&realm->inodes_with_caps_lock);
    + list_del_init(&ci->i_snap_realm_item);
    + ci->i_snap_realm_counter++;
    + ci->i_snap_realm = NULL;
    + spin_unlock(&realm->inodes_with_caps_lock);
    + ceph_put_snap_realm(mdsc, realm);
    + }
    + if (!__ceph_is_any_real_caps(ci))
    + __cap_delay_cancel(mdsc, ci);
    +}
    +
    +/*
    + * Build and send a cap message to the given MDS.
    + *
    + * Caller should be holding s_mutex.
    + */
    +static void send_cap_msg(struct ceph_mds_client *mdsc, u64 ino, u64 cid, int op,
    + int caps, int wanted, int dirty,
    + u32 seq, u64 flush_tid, u32 issue_seq, u32 mseq,
    + u64 size, u64 max_size,
    + struct timespec *mtime, struct timespec *atime,
    + u64 time_warp_seq,
    + uid_t uid, gid_t gid, mode_t mode,
    + u64 xattr_version,
    + void *xattrs_blob, int xattrs_blob_size,
    + u64 follows, int mds)
    +{
    + struct ceph_mds_caps *fc;
    + struct ceph_msg *msg;
    +
    + dout("send_cap_msg %s %llx %llx caps %s wanted %s dirty %s"
    + " seq %u/%u mseq %u follows %lld size %llu/%llu"
    + " xattr_ver %llu xattr_len %d\n", ceph_cap_op_name(op),
    + cid, ino, ceph_cap_string(caps), ceph_cap_string(wanted),
    + ceph_cap_string(dirty),
    + seq, issue_seq, mseq, follows, size, max_size,
    + xattr_version, xattrs_blob_size);
    +
    + msg = ceph_msg_new(CEPH_MSG_CLIENT_CAPS, sizeof(*fc) + xattrs_blob_size,
    + 0, 0, NULL);
    + if (IS_ERR(msg))
    + return;
    +
    + fc = msg->front.iov_base;
    +
    + memset(fc, 0, sizeof(*fc));
    +
    + fc->cap_id = cpu_to_le64(cid);
    + fc->op = cpu_to_le32(op);
    + fc->seq = cpu_to_le32(seq);
    + fc->client_tid = cpu_to_le64(flush_tid);
    + fc->issue_seq = cpu_to_le32(issue_seq);
    + fc->migrate_seq = cpu_to_le32(mseq);
    + fc->caps = cpu_to_le32(caps);
    + fc->wanted = cpu_to_le32(wanted);
    + fc->dirty = cpu_to_le32(dirty);
    + fc->ino = cpu_to_le64(ino);
    + fc->snap_follows = cpu_to_le64(follows);
    +
    + fc->size = cpu_to_le64(size);
    + fc->max_size = cpu_to_le64(max_size);
    + if (mtime)
    + ceph_encode_timespec(&fc->mtime, mtime);
    + if (atime)
    + ceph_encode_timespec(&fc->atime, atime);
    + fc->time_warp_seq = cpu_to_le32(time_warp_seq);
    +
    + fc->uid = cpu_to_le32(uid);
    + fc->gid = cpu_to_le32(gid);
    + fc->mode = cpu_to_le32(mode);
    +
    + fc->xattr_version = cpu_to_le64(xattr_version);
    + if (xattrs_blob) {
    + char *dst = (char *)fc;
    + dst += sizeof(*fc);
    +
    + fc->xattr_len = cpu_to_le32(xattrs_blob_size);
    + memcpy(dst, xattrs_blob, xattrs_blob_size);
    + }
    +
    + ceph_send_msg_mds(mdsc, msg, mds);
    +}
    +
    +/*
    + * Queue cap releases when an inode is dropped from our
    + * cache.
    + */
    +void ceph_queue_caps_release(struct inode *inode)
    +{
    + struct ceph_inode_info *ci = ceph_inode(inode);
    + struct rb_node *p;
    +
    + spin_lock(&inode->i_lock);
    + p = rb_first(&ci->i_caps);
    + while (p) {
    + struct ceph_cap *cap = rb_entry(p, struct ceph_cap, ci_node);
    + struct ceph_mds_session *session = cap->session;
    + struct ceph_msg *msg;
    + struct ceph_mds_cap_release *head;
    + struct ceph_mds_cap_item *item;
    +
    + spin_lock(&session->s_cap_lock);
    + BUG_ON(!session->s_num_cap_releases);
    + msg = list_first_entry(&session->s_cap_releases,
    + struct ceph_msg, list_head);
    +
    + dout(" adding %p release to mds%d msg %p (%d left)\n",
    + inode, session->s_mds, msg, session->s_num_cap_releases);
    +
    + BUG_ON(msg->front.iov_len + sizeof(*item) > PAGE_CACHE_SIZE);
    + head = msg->front.iov_base;
    + head->num = cpu_to_le32(le32_to_cpu(head->num) + 1);
    + item = msg->front.iov_base + msg->front.iov_len;
    + item->ino = cpu_to_le64(ceph_ino(inode));
    + item->cap_id = cpu_to_le64(cap->cap_id);
    + item->migrate_seq = cpu_to_le32(cap->mseq);
    + item->seq = cpu_to_le32(cap->issue_seq);
    +
    + session->s_num_cap_releases--;
    +
    + msg->front.iov_len += sizeof(*item);
    + if (le32_to_cpu(head->num) == CEPH_CAPS_PER_RELEASE) {
    + dout(" release msg %p full\n", msg);
    + list_move_tail(&msg->list_head,
    + &session->s_cap_releases_done);
    + } else {
    + dout(" release msg %p at %d/%d (%d)\n", msg,
    + (int)le32_to_cpu(head->num),
    + (int)CEPH_CAPS_PER_RELEASE,
    + (int)msg->front.iov_len);
    + }
    + spin_unlock(&session->s_cap_lock);
    + p = rb_next(p);
    + __ceph_remove_cap(cap, NULL);
    +
    + }
    + spin_unlock(&inode->i_lock);
    +}
    +
    +/*
    + * Send a cap msg on the given inode. Update our caps state, then
    + * drop i_lock and send the message.
    + *
    + * Make note of max_size reported/requested from mds, revoked caps
    + * that have now been implemented.
    + *
    + * Make half-hearted attempt ot to invalidate page cache if we are
    + * dropping RDCACHE. Note that this will leave behind locked pages
    + * that we'll then need to deal with elsewhere.
    + *
    + * Return non-zero if delayed release.
    + *
    + * called with i_lock, then drops it.
    + * caller should hold snap_rwsem (read), s_mutex.
    + */
    +static int __send_cap(struct ceph_mds_client *mdsc, struct ceph_cap *cap,
    + int op, int used, int want, int retain, int flushing,
    + unsigned *pflush_tid)
    + __releases(cap->ci->vfs_inode->i_lock)
    +{
    + struct ceph_inode_info *ci = cap->ci;
    + struct inode *inode = &ci->vfs_inode;
    + u64 cap_id = cap->cap_id;
    + int held = cap->issued | cap->implemented;
    + int revoking = cap->implemented & ~cap->issued;
    + int dropping = cap->issued & ~retain;
    + int keep;
    + u64 seq, issue_seq, mseq, time_warp_seq, follows;
    + u64 size, max_size;
    + struct timespec mtime, atime;
    + int wake = 0;
    + mode_t mode;
    + uid_t uid;
    + gid_t gid;
    + int mds = cap->session->s_mds;
    + void *xattrs_blob = NULL;
    + int xattrs_blob_size = 0;
    + u64 xattr_version = 0;
    + int delayed = 0;
    + u64 flush_tid = 0;
    + int i;
    +
    + dout("__send_cap %p cap %p session %p %s -> %s (revoking %s)\n",
    + inode, cap, cap->session,
    + ceph_cap_string(held), ceph_cap_string(held & retain),
    + ceph_cap_string(revoking));
    + BUG_ON((retain & CEPH_CAP_PIN) == 0);
    +
    + /* don't release wanted unless we've waited a bit. */
    + if ((ci->i_ceph_flags & CEPH_I_NODELAY) == 0 &&
    + time_before(jiffies, ci->i_hold_caps_min)) {
    + dout(" delaying issued %s -> %s, wanted %s -> %s on send\n",
    + ceph_cap_string(cap->issued),
    + ceph_cap_string(cap->issued & retain),
    + ceph_cap_string(cap->mds_wanted),
    + ceph_cap_string(want));
    + want |= cap->mds_wanted;
    + retain |= cap->issued;
    + delayed = 1;
    + }
    + ci->i_ceph_flags &= ~(CEPH_I_NODELAY | CEPH_I_FLUSH);
    +
    + cap->issued &= retain; /* drop bits we don't want */
    + if (cap->implemented & ~cap->issued) {
    + /*
    + * Wake up any waiters on wanted -> needed transition.
    + * This is due to the weird transition from buffered
    + * to sync IO... we need to flush dirty pages _before_
    + * allowing sync writes to avoid reordering.
    + */
    + wake = 1;
    + }
    + cap->implemented &= cap->issued | used;
    + cap->mds_wanted = want;
    +
    + if (flushing) {
    + /*
    + * assign a tid for flush operations so we can avoid
    + * flush1 -> dirty1 -> flush2 -> flushack1 -> mark
    + * clean type races. track latest tid for every bit
    + * so we can handle flush AxFw, flush Fw, and have the
    + * first ack clean Ax.
    + */
    + flush_tid = ++ci->i_cap_flush_last_tid;
    + if (pflush_tid)
    + *pflush_tid = flush_tid;
    + dout(" cap_flush_tid %d\n", (int)flush_tid);
    + for (i = 0; i < CEPH_CAP_BITS; i++)
    + if (flushing & (1 << i))
    + ci->i_cap_flush_tid[i] = flush_tid;
    + }
    +
    + keep = cap->implemented;
    + seq = cap->seq;
    + issue_seq = cap->issue_seq;
    + mseq = cap->mseq;
    + size = inode->i_size;
    + ci->i_reported_size = size;
    + max_size = ci->i_wanted_max_size;
    + ci->i_requested_max_size = max_size;
    + mtime = inode->i_mtime;
    + atime = inode->i_atime;
    + time_warp_seq = ci->i_time_warp_seq;
    + follows = ci->i_snap_realm->cached_context->seq;
    + uid = inode->i_uid;
    + gid = inode->i_gid;
    + mode = inode->i_mode;
    +
    + if (dropping & CEPH_CAP_XATTR_EXCL) {
    + __ceph_build_xattrs_blob(ci, &xattrs_blob, &xattrs_blob_size);
    + ci->i_xattrs.prealloc_blob = NULL;
    + ci->i_xattrs.prealloc_size = 0;
    + xattr_version = ci->i_xattrs.version + 1;
    + }
    +
    + spin_unlock(&inode->i_lock);
    +
    + if (dropping & CEPH_CAP_FILE_CACHE) {
    + /* invalidate what we can */
    + dout("invalidating pages on %p\n", inode);
    + invalidate_mapping_pages(&inode->i_data, 0, -1);
    + }
    +
    + send_cap_msg(mdsc, ceph_vino(inode).ino, cap_id,
    + op, keep, want, flushing, seq, flush_tid, issue_seq, mseq,
    + size, max_size, &mtime, &atime, time_warp_seq,
    + uid, gid, mode,
    + xattr_version,
    + xattrs_blob, xattrs_blob_size,
    + follows, mds);
    +
    + kfree(xattrs_blob);
    +
    + if (wake)
    + wake_up(&ci->i_cap_wq);
    +
    + return delayed;
    +}
    +
    +/*
    + * When a snapshot is taken, clients accumulate dirty metadata on
    + * inodes with capabilities in ceph_cap_snaps to describe the file
    + * state at the time the snapshot was taken. This must be flushed
    + * asynchronously back to the MDS once sync writes complete and dirty
    + * data is written out.
    + *
    + * Called under i_lock. Takes s_mutex as needed.
    + */
    +void __ceph_flush_snaps(struct ceph_inode_info *ci,
    + struct ceph_mds_session **psession)
    +{
    + struct inode *inode = &ci->vfs_inode;
    + int mds;
    + struct ceph_cap_snap *capsnap;
    + u32 mseq;
    + struct ceph_mds_client *mdsc = &ceph_inode_to_client(inode)->mdsc;
    + struct ceph_mds_session *session = NULL; /* if session != NULL, we hold
    + session->s_mutex */
    + u64 next_follows = 0; /* keep track of how far we've gotten through the
    + i_cap_snaps list, and skip these entries next time
    + around to avoid an infinite loop */
    +
    + if (psession)
    + session = *psession;
    +
    + dout("__flush_snaps %p\n", inode);
    +retry:
    + list_for_each_entry(capsnap, &ci->i_cap_snaps, ci_item) {
    + /* avoid an infiniute loop after retry */
    + if (capsnap->follows < next_follows)
    + continue;
    + /*
    + * we need to wait for sync writes to complete and for dirty
    + * pages to be written out.
    + */
    + if (capsnap->dirty_pages || capsnap->writing)
    + continue;
    +
    + /* pick mds, take s_mutex */
    + mds = __ceph_get_cap_mds(ci, &mseq);
    + if (session && session->s_mds != mds) {
    + dout("oops, wrong session %p mutex\n", session);
    + mutex_unlock(&session->s_mutex);
    + ceph_put_mds_session(session);
    + session = NULL;
    + }
    + if (!session) {
    + spin_unlock(&inode->i_lock);
    + mutex_lock(&mdsc->mutex);
    + session = __ceph_lookup_mds_session(mdsc, mds);
    + mutex_unlock(&mdsc->mutex);
    + if (session) {
    + dout("inverting session/ino locks on %p\n",
    + session);
    + mutex_lock(&session->s_mutex);
    + }
    + /*
    + * if session == NULL, we raced against a cap
    + * deletion. retry, and we'll get a better
    + * @mds value next time.
    + */
    + spin_lock(&inode->i_lock);
    + goto retry;
    + }
    +
    + capsnap->flush_tid = ++ci->i_cap_flush_last_tid;
    + atomic_inc(&capsnap->nref);
    + if (!list_empty(&capsnap->flushing_item))
    + list_del_init(&capsnap->flushing_item);
    + list_add_tail(&capsnap->flushing_item,
    + &session->s_cap_snaps_flushing);
    + spin_unlock(&inode->i_lock);
    +
    + dout("flush_snaps %p cap_snap %p follows %lld size %llu\n",
    + inode, capsnap, next_follows, capsnap->size);
    + send_cap_msg(mdsc, ceph_vino(inode).ino, 0,
    + CEPH_CAP_OP_FLUSHSNAP, capsnap->issued, 0,
    + capsnap->dirty, 0, capsnap->flush_tid, 0, mseq,
    + capsnap->size, 0,
    + &capsnap->mtime, &capsnap->atime,
    + capsnap->time_warp_seq,
    + capsnap->uid, capsnap->gid, capsnap->mode,
    + 0, NULL, 0,
    + capsnap->follows, mds);
    +
    + next_follows = capsnap->follows + 1;
    + ceph_put_cap_snap(capsnap);
    +
    + spin_lock(&inode->i_lock);
    + goto retry;
    + }
    +
    + /* we flushed them all; remove this inode from the queue */
    + spin_lock(&mdsc->snap_flush_lock);
    + list_del_init(&ci->i_snap_flush_item);
    + spin_unlock(&mdsc->snap_flush_lock);
    +
    + if (psession)
    + *psession = session;
    + else if (session) {
    + mutex_unlock(&session->s_mutex);
    + ceph_put_mds_session(session);
    + }
    +}
    +
    +static void ceph_flush_snaps(struct ceph_inode_info *ci)
    +{
    + struct inode *inode = &ci->vfs_inode;
    +
    + spin_lock(&inode->i_lock);
    + __ceph_flush_snaps(ci, NULL);
    + spin_unlock(&inode->i_lock);
    +}
    +
    +/*
    + * Add dirty inode to the flushing list. Assigned a seq number so we
    + * can wait for caps to flush without starving.
    + */
    +static void __mark_caps_flushing(struct inode *inode,
    + struct ceph_mds_session *session)
    +{
    + struct ceph_mds_client *mdsc = &ceph_client(inode->i_sb)->mdsc;
    + struct ceph_inode_info *ci = ceph_inode(inode);
    +
    + BUG_ON(list_empty(&ci->i_dirty_item));
    + spin_lock(&mdsc->cap_dirty_lock);
    + if (list_empty(&ci->i_flushing_item)) {
    + list_add_tail(&ci->i_flushing_item, &session->s_cap_flushing);
    + mdsc->num_cap_flushing++;
    + ci->i_cap_flush_seq = ++mdsc->cap_flush_seq;
    + dout(" inode %p now flushing seq %lld\n", &ci->vfs_inode,
    + ci->i_cap_flush_seq);
    + }
    + spin_unlock(&mdsc->cap_dirty_lock);
    +}
    +
    +/*
    + * Swiss army knife function to examine currently used and wanted
    + * versus held caps. Release, flush, ack revoked caps to mds as
    + * appropriate.
    + *
    + * CHECK_CAPS_NODELAY - caller is delayed work and we should not delay
    + * cap release further.
    + * CHECK_CAPS_AUTHONLY - we should only check the auth cap
    + * CHECK_CAPS_FLUSH - we should flush any dirty caps immediately, without
    + * further delay.
    + */
    +void ceph_check_caps(struct ceph_inode_info *ci, int flags,
    + struct ceph_mds_session *session)
    +{
    + struct ceph_client *client = ceph_inode_to_client(&ci->vfs_inode);
    + struct ceph_mds_client *mdsc = &client->mdsc;
    + struct inode *inode = &ci->vfs_inode;
    + struct ceph_cap *cap;
    + int file_wanted, used;
    + int took_snap_rwsem = 0; /* true if mdsc->snap_rwsem held */
    + int drop_session_lock = session ? 0 : 1;
    + int want, retain, revoking, flushing = 0;
    + int mds = -1; /* keep track of how far we've gone through i_caps list
    + to avoid an infinite loop on retry */
    + struct rb_node *p;
    + int tried_invalidate = 0;
    + int delayed = 0, sent = 0, force_requeue = 0, num;
    + int is_delayed = flags & CHECK_CAPS_NODELAY;
    +
    + /* if we are unmounting, flush any unused caps immediately. */
    + if (mdsc->stopping)
    + is_delayed = 1;
    +
    + spin_lock(&inode->i_lock);
    +
    + if (ci->i_ceph_flags & CEPH_I_FLUSH)
    + flags |= CHECK_CAPS_FLUSH;
    +
    + /* flush snaps first time around only */
    + if (!list_empty(&ci->i_cap_snaps))
    + __ceph_flush_snaps(ci, &session);
    + goto retry_locked;
    +retry:
    + spin_lock(&inode->i_lock);
    +retry_locked:
    + file_wanted = __ceph_caps_file_wanted(ci);
    + used = __ceph_caps_used(ci);
    + want = file_wanted | used;
    +
    + retain = want | CEPH_CAP_PIN;
    + if (!mdsc->stopping && inode->i_nlink > 0) {
    + if (want) {
    + retain |= CEPH_CAP_ANY; /* be greedy */
    + } else {
    + retain |= CEPH_CAP_ANY_SHARED;
    + /*
    + * keep RD only if we didn't have the file open RW,
    + * because then the mds would revoke it anyway to
    + * journal max_size=0.
    + */
    + if (ci->i_max_size == 0)
    + retain |= CEPH_CAP_ANY_RD;
    + }
    + }
    +
    + dout("check_caps %p file_want %s used %s dirty %s flushing %s"
    + " issued %s retain %s %s%s%s\n", inode,
    + ceph_cap_string(file_wanted),
    + ceph_cap_string(used), ceph_cap_string(ci->i_dirty_caps),
    + ceph_cap_string(ci->i_flushing_caps),
    + ceph_cap_string(__ceph_caps_issued(ci, NULL)),
    + ceph_cap_string(retain),
    + (flags & CHECK_CAPS_AUTHONLY) ? " AUTHONLY" : "",
    + (flags & CHECK_CAPS_NODELAY) ? " NODELAY" : "",
    + (flags & CHECK_CAPS_FLUSH) ? " FLUSH" : "");
    +
    + /*
    + * If we no longer need to hold onto old our caps, and we may
    + * have cached pages, but don't want them, then try to invalidate.
    + * If we fail, it's because pages are locked.... try again later.
    + */
    + if ((!is_delayed || mdsc->stopping) &&
    + ci->i_wrbuffer_ref == 0 && /* no dirty pages... */
    + ci->i_rdcache_gen && /* may have cached pages */
    + file_wanted == 0 && /* no open files */
    + !tried_invalidate) {
    + u32 invalidating_gen = ci->i_rdcache_gen;
    + int ret;
    +
    + dout("check_caps trying to invalidate on %p\n", inode);
    + spin_unlock(&inode->i_lock);
    + ret = invalidate_inode_pages2(&inode->i_data);
    + spin_lock(&inode->i_lock);
    + if (ret == 0 && invalidating_gen == ci->i_rdcache_gen) {
    + /* success. */
    + ci->i_rdcache_gen = 0;
    + ci->i_rdcache_revoking = 0;
    + } else {
    + dout("check_caps failed to invalidate pages\n");
    + /* we failed to invalidate pages. check these
    + caps again later. */
    + force_requeue = 1;
    + __cap_set_timeouts(mdsc, ci);
    + }
    + tried_invalidate = 1;
    + goto retry_locked;
    + }
    +
    + num = 0;
    + for (p = rb_first(&ci->i_caps); p; p = rb_next(p)) {
    + cap = rb_entry(p, struct ceph_cap, ci_node);
    + num++;
    +
    + /* avoid looping forever */
    + if (mds >= cap->mds ||
    + ((flags & CHECK_CAPS_AUTHONLY) && cap != ci->i_auth_cap))
    + continue;
    +
    + /* NOTE: no side-effects allowed, until we take s_mutex */
    +
    + revoking = cap->implemented & ~cap->issued;
    + if (revoking)
    + dout("mds%d revoking %s\n", cap->mds,
    + ceph_cap_string(revoking));
    +
    + if (cap == ci->i_auth_cap &&
    + (cap->issued & CEPH_CAP_FILE_WR)) {
    + /* request larger max_size from MDS? */
    + if (ci->i_wanted_max_size > ci->i_max_size &&
    + ci->i_wanted_max_size > ci->i_requested_max_size) {
    + dout("requesting new max_size\n");
    + goto ack;
    + }
    +
    + /* approaching file_max? */
    + if ((inode->i_size << 1) >= ci->i_max_size &&
    + (ci->i_reported_size << 1) < ci->i_max_size) {
    + dout("i_size approaching max_size\n");
    + goto ack;
    + }
    + }
    + /* flush anything dirty? */
    + if (cap == ci->i_auth_cap && (flags & CHECK_CAPS_FLUSH) &&
    + ci->i_dirty_caps) {
    + dout("flushing dirty caps\n");
    + goto ack;
    + }
    +
    + /* completed revocation? going down and there are no caps? */
    + if (revoking && (revoking & used) == 0) {
    + dout("completed revocation of %s\n",
    + ceph_cap_string(cap->implemented & ~cap->issued));
    + goto ack;
    + }
    +
    + /* want more caps from mds? */
    + if (want & ~(cap->mds_wanted | cap->issued))
    + goto ack;
    +
    + /* things we might delay */
    + if ((cap->issued & ~retain) == 0 &&
    + cap->mds_wanted == want)
    + continue; /* nope, all good */
    +
    + if (is_delayed)
    + goto ack;
    +
    + /* delay? */
    + if ((ci->i_ceph_flags & CEPH_I_NODELAY) == 0 &&
    + time_before(jiffies, ci->i_hold_caps_max)) {
    + dout(" delaying issued %s -> %s, wanted %s -> %s\n",
    + ceph_cap_string(cap->issued),
    + ceph_cap_string(cap->issued & retain),
    + ceph_cap_string(cap->mds_wanted),
    + ceph_cap_string(want));
    + delayed++;
    + continue;
    + }
    +
    +ack:
    + if (session && session != cap->session) {
    + dout("oops, wrong session %p mutex\n", session);
    + mutex_unlock(&session->s_mutex);
    + session = NULL;
    + }
    + if (!session) {
    + session = cap->session;
    + if (mutex_trylock(&session->s_mutex) == 0) {
    + dout("inverting session/ino locks on %p\n",
    + session);
    + spin_unlock(&inode->i_lock);
    + if (took_snap_rwsem) {
    + up_read(&mdsc->snap_rwsem);
    + took_snap_rwsem = 0;
    + }
    + mutex_lock(&session->s_mutex);
    + goto retry;
    + }
    + }
    + /* take snap_rwsem after session mutex */
    + if (!took_snap_rwsem) {
    + if (down_read_trylock(&mdsc->snap_rwsem) == 0) {
    + dout("inverting snap/in locks on %p\n",
    + inode);
    + spin_unlock(&inode->i_lock);
    + down_read(&mdsc->snap_rwsem);
    + took_snap_rwsem = 1;
    + goto retry;
    + }
    + took_snap_rwsem = 1;
    + }
    +
    + if (cap == ci->i_auth_cap && ci->i_dirty_caps) {
    + /* update dirty, flushing bits */
    + flushing = ci->i_dirty_caps;
    + dout(" flushing %s, flushing_caps %s -> %s\n",
    + ceph_cap_string(flushing),
    + ceph_cap_string(ci->i_flushing_caps),
    + ceph_cap_string(ci->i_flushing_caps | flushing));
    + ci->i_flushing_caps |= flushing;
    + ci->i_dirty_caps = 0;
    + __mark_caps_flushing(inode, session);
    + }
    +
    + mds = cap->mds; /* remember mds, so we don't repeat */
    + sent++;
    +
    + /* __send_cap drops i_lock */
    + delayed += __send_cap(mdsc, cap, CEPH_CAP_OP_UPDATE, used, want,
    + retain, flushing, NULL);
    + goto retry; /* retake i_lock and restart our cap scan. */
    + }
    +
    + /*
    + * Reschedule delayed caps release if we delayed anything,
    + * otherwise cancel.
    + */
    + if (delayed && is_delayed)
    + force_requeue = 1; /* __send_cap delayed release; requeue */
    + if (!delayed && !is_delayed)
    + __cap_delay_cancel(mdsc, ci);
    + else if (!is_delayed || force_requeue)
    + __cap_delay_requeue(mdsc, ci);
    +
    + spin_unlock(&inode->i_lock);
    +
    + if (session && drop_session_lock)
    + mutex_unlock(&session->s_mutex);
    + if (took_snap_rwsem)
    + up_read(&mdsc->snap_rwsem);
    +}
    +
    +/*
    + * Mark caps dirty. If inode is newly dirty, add to the global dirty
    + * list.
    + */
    +int __ceph_mark_dirty_caps(struct ceph_inode_info *ci, int mask)
    +{
    + struct ceph_mds_client *mdsc = &ceph_client(ci->vfs_inode.i_sb)->mdsc;
    + struct inode *inode = &ci->vfs_inode;
    + int was = __ceph_caps_dirty(ci);
    + int dirty = 0;
    +
    + dout("__mark_dirty_caps %p %s dirty %s -> %s\n", &ci->vfs_inode,
    + ceph_cap_string(mask), ceph_cap_string(ci->i_dirty_caps),
    + ceph_cap_string(ci->i_dirty_caps | mask));
    + ci->i_dirty_caps |= mask;
    + if (!was) {
    + dout(" inode %p now dirty\n", &ci->vfs_inode);
    + spin_lock(&mdsc->cap_dirty_lock);
    + list_add(&ci->i_dirty_item, &mdsc->cap_dirty);
    + spin_unlock(&mdsc->cap_dirty_lock);
    + igrab(inode);
    + dirty |= I_DIRTY_SYNC;
    + }
    + if ((was & CEPH_CAP_FILE_BUFFER) &&
    + (mask & CEPH_CAP_FILE_BUFFER))
    + dirty |= I_DIRTY_DATASYNC;
    + if (dirty)
    + __mark_inode_dirty(inode, dirty);
    + __cap_delay_requeue(mdsc, ci);
    + return was;
    +}
    +
    +/*
    + * Try to flush dirty caps back to the auth mds.
    + */
    +static int try_flush_caps(struct inode *inode, struct ceph_mds_session *session,
    + unsigned *flush_tid)
    +{
    + struct ceph_mds_client *mdsc = &ceph_client(inode->i_sb)->mdsc;
    + struct ceph_inode_info *ci = ceph_inode(inode);
    + int unlock_session = session ? 0 : 1;
    + int flushing = 0;
    +
    +retry:
    + spin_lock(&inode->i_lock);
    + if (ci->i_dirty_caps && ci->i_auth_cap) {
    + struct ceph_cap *cap = ci->i_auth_cap;
    + int used = __ceph_caps_used(ci);
    + int want = __ceph_caps_wanted(ci);
    +
    + if (!session) {
    + spin_unlock(&inode->i_lock);
    + session = cap->session;
    + mutex_lock(&session->s_mutex);
    + goto retry;
    + }
    + BUG_ON(session != cap->session);
    + if (cap->session->s_state < CEPH_MDS_SESSION_OPEN)
    + goto out;
    +
    + __mark_caps_flushing(inode, session);
    +
    + flushing = ci->i_dirty_caps;
    + dout(" flushing %s, flushing_caps %s -> %s\n",
    + ceph_cap_string(flushing),
    + ceph_cap_string(ci->i_flushing_caps),
    + ceph_cap_string(ci->i_flushing_caps | flushing));
    + ci->i_flushing_caps |= flushing;
    + ci->i_dirty_caps = 0;
    +
    + /* __send_cap drops i_lock */
    + __send_cap(mdsc, cap, CEPH_CAP_OP_FLUSH, used, want,
    + cap->issued | cap->implemented, flushing,
    + flush_tid);
    + goto out_unlocked;
    + }
    +out:
    + spin_unlock(&inode->i_lock);
    +out_unlocked:
    + if (session && unlock_session)
    + mutex_unlock(&session->s_mutex);
    + return flushing;
    +}
    +
    +/*
    + * Return true if we've flushed caps through the given flush_tid.
    + */
    +static int caps_are_flushed(struct inode *inode, unsigned tid)
    +{
    + struct ceph_inode_info *ci = ceph_inode(inode);
    + int dirty, i, ret = 1;
    +
    + spin_lock(&inode->i_lock);
    + dirty = __ceph_caps_dirty(ci);
    + for (i = 0; i < CEPH_CAP_BITS; i++)
    + if ((ci->i_flushing_caps & (1 << i)) &&
    + ci->i_cap_flush_tid[i] <= tid) {
    + /* still flushing this bit */
    + ret = 0;
    + break;
    + }
    + spin_unlock(&inode->i_lock);
    + return ret;
    +}
    +
    +/*
    + * Wait on any unsafe replies for the given inode. First wait on the
    + * newest request, and make that the upper bound. Then, if there are
    + * more requests, keep waiting on the oldest as long as it is still older
    + * than the original request.
    + */
    +static void sync_write_wait(struct inode *inode)
    +{
    + struct ceph_inode_info *ci = ceph_inode(inode);
    + struct list_head *head = &ci->i_unsafe_writes;
    + struct ceph_osd_request *req;
    + u64 last_tid;
    +
    + spin_lock(&ci->i_unsafe_lock);
    + if (list_empty(head))
    + goto out;
    +
    + /* set upper bound as _last_ entry in chain */
    + req = list_entry(head->prev, struct ceph_osd_request,
    + r_unsafe_item);
    + last_tid = req->r_tid;
    +
    + do {
    + ceph_osdc_get_request(req);
    + spin_unlock(&ci->i_unsafe_lock);
    + dout("sync_write_wait on tid %llu (until %llu)\n",
    + req->r_tid, last_tid);
    + wait_for_completion(&req->r_safe_completion);
    + spin_lock(&ci->i_unsafe_lock);
    + ceph_osdc_put_request(req);
    +
    + /*
    + * from here on look at first entry in chain, since we
    + * only want to wait for anything older than last_tid
    + */
    + if (list_empty(head))
    + break;
    + req = list_entry(head->next, struct ceph_osd_request,
    + r_unsafe_item);
    + } while (req->r_tid < last_tid);
    +out:
    + spin_unlock(&ci->i_unsafe_lock);
    +}
    +
    +int ceph_fsync(struct file *file, struct dentry *dentry, int datasync)
    +{
    + struct inode *inode = dentry->d_inode;
    + struct ceph_inode_info *ci = ceph_inode(inode);
    + unsigned flush_tid;
    + int ret;
    + int dirty;
    +
    + dout("fsync %p%s\n", inode, datasync ? " datasync" : "");
    + sync_write_wait(inode);
    +
    + ret = filemap_write_and_wait(inode->i_mapping);
    + if (ret < 0)
    + return ret;
    +
    + dirty = try_flush_caps(inode, NULL, &flush_tid);
    + dout("fsync dirty caps are %s\n", ceph_cap_string(dirty));
    +
    + /*
    + * only wait on non-file metadata writeback (the mds
    + * can recover size and mtime, so we don't need to
    + * wait for that)
    + */
    + if (!datasync && (dirty & ~CEPH_CAP_ANY_FILE_WR)) {
    + dout("fsync waiting for flush_tid %u\n", flush_tid);
    + ret = wait_event_interruptible(ci->i_cap_wq,
    + caps_are_flushed(inode, flush_tid));
    + }
    +
    + dout("fsync %p%s done\n", inode, datasync ? " datasync" : "");
    + return ret;
    +}
    +
    +/*
    + * Flush any dirty caps back to the mds. If we aren't asked to wait,
    + * queue inode for flush but don't do so immediately, because we can
    + * get by with fewer MDS messages if we wait for data writeback to
    + * complete first.
    + */
    +int ceph_write_inode(struct inode *inode, int wait)
    +{
    + struct ceph_inode_info *ci = ceph_inode(inode);
    + unsigned flush_tid;
    + int err = 0;
    + int dirty;
    +
    + dout("write_inode %p wait=%d\n", inode, wait);
    + if (wait) {
    + dirty = try_flush_caps(inode, NULL, &flush_tid);
    + if (dirty)
    + err = wait_event_interruptible(ci->i_cap_wq,
    + caps_are_flushed(inode, flush_tid));
    + } else {
    + struct ceph_mds_client *mdsc = &ceph_client(inode->i_sb)->mdsc;
    +
    + spin_lock(&inode->i_lock);
    + if (__ceph_caps_dirty(ci))
    + __cap_delay_requeue_front(mdsc, ci);
    + spin_unlock(&inode->i_lock);
    + }
    + return err;
    +}
    +
    +/*
    + * After a recovering MDS goes active, we need to resend any caps
    + * we were flushing.
    + *
    + * Caller holds session->s_mutex.
    + */
    +void ceph_kick_flushing_caps(struct ceph_mds_client *mdsc,
    + struct ceph_mds_session *session)
    +{
    + struct ceph_inode_info *ci;
    + struct ceph_cap_snap *capsnap;
    +
    + dout("kick_flushing_caps mds%d\n", session->s_mds);
    + list_for_each_entry(capsnap, &session->s_cap_snaps_flushing,
    + flushing_item) {
    + struct ceph_inode_info *ci = capsnap->ci;
    + struct inode *inode = &ci->vfs_inode;
    + struct ceph_cap *cap;
    +
    + spin_lock(&inode->i_lock);
    + cap = ci->i_auth_cap;
    + if (cap && cap->session == session) {
    + dout("kick_flushing_caps %p cap %p capsnap %p\n", inode,
    + cap, capsnap);
    + __ceph_flush_snaps(ci, &session);
    + } else {
    + pr_err("ceph %p auth cap %p not mds%d ???\n", inode,
    + cap, session->s_mds);
    + spin_unlock(&inode->i_lock);
    + }
    + }
    +
    + list_for_each_entry(ci, &session->s_cap_flushing, i_flushing_item) {
    + struct inode *inode = &ci->vfs_inode;
    + struct ceph_cap *cap;
    +
    + spin_lock(&inode->i_lock);
    + cap = ci->i_auth_cap;
    + if (cap && cap->session == session) {
    + dout("kick_flushing_caps %p cap %p %s\n", inode,
    + cap, ceph_cap_string(ci->i_flushing_caps));
    + __send_cap(mdsc, cap, CEPH_CAP_OP_FLUSH,
    + __ceph_caps_used(ci),
    + __ceph_caps_wanted(ci),
    + cap->issued | cap->implemented,
    + ci->i_flushing_caps, NULL);
    + } else {
    + pr_err("ceph %p auth cap %p not mds%d ???\n", inode,
    + cap, session->s_mds);
    + spin_unlock(&inode->i_lock);
    + }
    + }
    +}
    +
    +
    +/*
    + * Take references to capabilities we hold, so that we don't release
    + * them to the MDS prematurely.
    + *
    + * Protected by i_lock.
    + */
    +static void __take_cap_refs(struct ceph_inode_info *ci, int got)
    +{
    + if (got & CEPH_CAP_PIN)
    + ci->i_pin_ref++;
    + if (got & CEPH_CAP_FILE_RD)
    + ci->i_rd_ref++;
    + if (got & CEPH_CAP_FILE_CACHE)
    + ci->i_rdcache_ref++;
    + if (got & CEPH_CAP_FILE_WR)
    + ci->i_wr_ref++;
    + if (got & CEPH_CAP_FILE_BUFFER) {
    + if (ci->i_wrbuffer_ref == 0)
    + igrab(&ci->vfs_inode);
    + ci->i_wrbuffer_ref++;
    + dout("__take_cap_refs %p wrbuffer %d -> %d (?)\n",
    + &ci->vfs_inode, ci->i_wrbuffer_ref-1, ci->i_wrbuffer_ref);
    + }
    +}
    +
    +/*
    + * Try to grab cap references. Specify those refs we @want, and the
    + * minimal set we @need. Also include the larger offset we are writing
    + * to (when applicable), and check against max_size here as well.
    + * Note that caller is responsible for ensuring max_size increases are
    + * requested from the MDS.
    + */
    +static int try_get_cap_refs(struct ceph_inode_info *ci, int need, int want,
    + int *got, loff_t endoff, int *check_max, int *err)
    +{
    + struct inode *inode = &ci->vfs_inode;
    + int ret = 0;
    + int have, implemented;
    +
    + dout("get_cap_refs %p need %s want %s\n", inode,
    + ceph_cap_string(need), ceph_cap_string(want));
    + spin_lock(&inode->i_lock);
    +
    + /* make sure we _have_ some caps! */
    + if (!__ceph_is_any_caps(ci)) {
    + dout("get_cap_refs %p no real caps\n", inode);
    + *err = -EBADF;
    + ret = 1;
    + goto out;
    + }
    +
    + if (need & CEPH_CAP_FILE_WR) {
    + if (endoff >= 0 && endoff > (loff_t)ci->i_max_size) {
    + dout("get_cap_refs %p endoff %llu > maxsize %llu\n",
    + inode, endoff, ci->i_max_size);
    + if (endoff > ci->i_wanted_max_size) {
    + *check_max = 1;
    + ret = 1;
    + }
    + goto out;
    + }
    + /*
    + * If a sync write is in progress, we must wait, so that we
    + * can get a final snapshot value for size+mtime.
    + */
    + if (__ceph_have_pending_cap_snap(ci)) {
    + dout("get_cap_refs %p cap_snap_pending\n", inode);
    + goto out;
    + }
    + }
    + have = __ceph_caps_issued(ci, &implemented);
    +
    + /*
    + * disallow writes while a truncate is pending
    + */
    + if (ci->i_truncate_pending)
    + have &= ~CEPH_CAP_FILE_WR;
    +
    + if ((have & need) == need) {
    + /*
    + * Look at (implemented & ~have & not) so that we keep waiting
    + * on transition from wanted -> needed caps. This is needed
    + * for WRBUFFER|WR -> WR to avoid a new WR sync write from
    + * going before a prior buffered writeback happens.
    + */
    + int not = want & ~(have & need);
    + int revoking = implemented & ~have;
    + dout("get_cap_refs %p have %s but not %s (revoking %s)\n",
    + inode, ceph_cap_string(have), ceph_cap_string(not),
    + ceph_cap_string(revoking));
    + if ((revoking & not) == 0) {
    + *got = need | (have & want);
    + __take_cap_refs(ci, *got);
    + ret = 1;
    + }
    + } else {
    + dout("get_cap_refs %p have %s needed %s\n", inode,
    + ceph_cap_string(have), ceph_cap_string(need));
    + }
    +out:
    + spin_unlock(&inode->i_lock);
    + dout("get_cap_refs %p ret %d got %s\n", inode,
    + ret, ceph_cap_string(*got));
    + return ret;
    +}
    +
    +/*
    + * Check the offset we are writing up to against our current
    + * max_size. If necessary, tell the MDS we want to write to
    + * a larger offset.
    + */
    +static void check_max_size(struct inode *inode, loff_t endoff)
    +{
    + struct ceph_inode_info *ci = ceph_inode(inode);
    + int check = 0;
    +
    + /* do we need to explicitly request a larger max_size? */
    + spin_lock(&inode->i_lock);
    + if ((endoff >= ci->i_max_size ||
    + endoff > (inode->i_size << 1)) &&
    + endoff > ci->i_wanted_max_size) {
    + dout("write %p at large endoff %llu, req max_size\n",
    + inode, endoff);
    + ci->i_wanted_max_size = endoff;
    + check = 1;
    + }
    + spin_unlock(&inode->i_lock);
    + if (check)
    + ceph_check_caps(ci, CHECK_CAPS_AUTHONLY, NULL);
    +}
    +
    +/*
    + * Wait for caps, and take cap references. If we can't get a WR cap
    + * due to a small max_size, make sure we check_max_size (and possibly
    + * ask the mds) so we don't get hung up indefinitely.
    + */
    +int ceph_get_caps(struct ceph_inode_info *ci, int need, int want, int *got,
    + loff_t endoff)
    +{
    + int check_max, ret, err;
    +
    +retry:
    + if (endoff > 0)
    + check_max_size(&ci->vfs_inode, endoff);
    + check_max = 0;
    + err = 0;
    + ret = wait_event_interruptible(ci->i_cap_wq,
    + try_get_cap_refs(ci, need, want,
    + got, endoff,
    + &check_max, &err));
    + if (err)
    + ret = err;
    + if (check_max)
    + goto retry;
    + return ret;
    +}
    +
    +/*
    + * Take cap refs. Caller must already know we hold at least one ref
    + * on the caps in question or we don't know this is safe.
    + */
    +void ceph_get_cap_refs(struct ceph_inode_info *ci, int caps)
    +{
    + spin_lock(&ci->vfs_inode.i_lock);
    + __take_cap_refs(ci, caps);
    + spin_unlock(&ci->vfs_inode.i_lock);
    +}
    +
    +/*
    + * Release cap refs.
    + *
    + * If we released the last ref on any given cap, call ceph_check_caps
    + * to release (or schedule a release).
    + *
    + * If we are releasing a WR cap (from a sync write), finalize any affected
    + * cap_snap, and wake up any waiters.
    + */
    +void ceph_put_cap_refs(struct ceph_inode_info *ci, int had)
    +{
    + struct inode *inode = &ci->vfs_inode;
    + int last = 0, flushsnaps = 0, wake = 0;
    + struct ceph_cap_snap *capsnap;
    +
    + spin_lock(&inode->i_lock);
    + if (had & CEPH_CAP_PIN)
    + --ci->i_pin_ref;
    + if (had & CEPH_CAP_FILE_RD)
    + if (--ci->i_rd_ref == 0)
    + last++;
    + if (had & CEPH_CAP_FILE_CACHE)
    + if (--ci->i_rdcache_ref == 0)
    + last++;
    + if (had & CEPH_CAP_FILE_BUFFER) {
    + if (--ci->i_wrbuffer_ref == 0)
    + last++;
    + dout("put_cap_refs %p wrbuffer %d -> %d (?)\n",
    + inode, ci->i_wrbuffer_ref+1, ci->i_wrbuffer_ref);
    + }
    + if (had & CEPH_CAP_FILE_WR)
    + if (--ci->i_wr_ref == 0) {
    + last++;
    + if (!list_empty(&ci->i_cap_snaps)) {
    + capsnap = list_first_entry(&ci->i_cap_snaps,
    + struct ceph_cap_snap,
    + ci_item);
    + if (capsnap->writing) {
    + capsnap->writing = 0;
    + flushsnaps =
    + __ceph_finish_cap_snap(ci,
    + capsnap);
    + wake = 1;
    + }
    + }
    + }
    + spin_unlock(&inode->i_lock);
    +
    + dout("put_cap_refs %p had %s %s\n", inode, ceph_cap_string(had),
    + last ? "last" : "");
    +
    + if (last && !flushsnaps)
    + ceph_check_caps(ci, 0, NULL);
    + else if (flushsnaps)
    + ceph_flush_snaps(ci);
    + if (wake)
    + wake_up(&ci->i_cap_wq);
    +}
    +
    +/*
    + * Release @nr WRBUFFER refs on dirty pages for the given @snapc snap
    + * context. Adjust per-snap dirty page accounting as appropriate.
    + * Once all dirty data for a cap_snap is flushed, flush snapped file
    + * metadata back to the MDS. If we dropped the last ref, call
    + * ceph_check_caps.
    + */
    +void ceph_put_wrbuffer_cap_refs(struct ceph_inode_info *ci, int nr,
    + struct ceph_snap_context *snapc)
    +{
    + struct inode *inode = &ci->vfs_inode;
    + int last = 0;
    + int last_snap = 0;
    + int found = 0;
    + struct ceph_cap_snap *capsnap = NULL;
    +
    + spin_lock(&inode->i_lock);
    + ci->i_wrbuffer_ref -= nr;
    + last = !ci->i_wrbuffer_ref;
    +
    + if (ci->i_head_snapc == snapc) {
    + ci->i_wrbuffer_ref_head -= nr;
    + if (!ci->i_wrbuffer_ref_head) {
    + ceph_put_snap_context(ci->i_head_snapc);
    + ci->i_head_snapc = NULL;
    + }
    + dout("put_wrbuffer_cap_refs on %p head %d/%d -> %d/%d %s\n",
    + inode,
    + ci->i_wrbuffer_ref+nr, ci->i_wrbuffer_ref_head+nr,
    + ci->i_wrbuffer_ref, ci->i_wrbuffer_ref_head,
    + last ? " LAST" : "");
    + } else {
    + list_for_each_entry(capsnap, &ci->i_cap_snaps, ci_item) {
    + if (capsnap->context == snapc) {
    + found = 1;
    + capsnap->dirty_pages -= nr;
    + last_snap = !capsnap->dirty_pages;
    + break;
    + }
    + }
    + BUG_ON(!found);
    + dout("put_wrbuffer_cap_refs on %p cap_snap %p "
    + " snap %lld %d/%d -> %d/%d %s%s\n",
    + inode, capsnap, capsnap->context->seq,
    + ci->i_wrbuffer_ref+nr, capsnap->dirty_pages + nr,
    + ci->i_wrbuffer_ref, capsnap->dirty_pages,
    + last ? " (wrbuffer last)" : "",
    + last_snap ? " (capsnap last)" : "");
    + }
    +
    + spin_unlock(&inode->i_lock);
    +
    + if (last) {
    + ceph_check_caps(ci, CHECK_CAPS_AUTHONLY, NULL);
    + iput(inode);
    + } else if (last_snap) {
    + ceph_flush_snaps(ci);
    + wake_up(&ci->i_cap_wq);
    + }
    +}
    +
    +/*
    + * Handle a cap GRANT message from the MDS. (Note that a GRANT may
    + * actually be a revocation if it specifies a smaller cap set.)
    + *
    + * caller holds s_mutex.
    + * return value:
    + * 0 - ok
    + * 1 - send the msg back to mds
    + * 2 - check_caps
    + */
    +static int handle_cap_grant(struct inode *inode, struct ceph_mds_caps *grant,
    + struct ceph_mds_session *session,
    + struct ceph_cap *cap,
    + void **xattr_data)
    + __releases(inode->i_lock)
    +
    +{
    + struct ceph_inode_info *ci = ceph_inode(inode);
    + int mds = session->s_mds;
    + int seq = le32_to_cpu(grant->seq);
    + int newcaps = le32_to_cpu(grant->caps);
    + int issued, implemented, used, wanted, dirty;
    + u64 size = le64_to_cpu(grant->size);
    + u64 max_size = le64_to_cpu(grant->max_size);
    + struct timespec mtime, atime, ctime;
    + int reply = 0;
    + int wake = 0;
    + int writeback = 0;
    + int revoked_rdcache = 0;
    + int invalidate_async = 0;
    + int tried_invalidate = 0;
    + int ret;
    +
    + dout("handle_cap_grant inode %p cap %p mds%d seq %d %s\n",
    + inode, cap, mds, seq, ceph_cap_string(newcaps));
    + dout(" size %llu max_size %llu, i_size %llu\n", size, max_size,
    + inode->i_size);
    +start:
    +
    + cap->gen = session->s_cap_gen;
    +
    + /*
    + * Each time we receive CACHE anew, we increment i_rdcache_gen.
    + * Also clear I_COMPLETE: we don't know what happened to this directory
    + */
    + if ((newcaps & CEPH_CAP_FILE_CACHE) && /* got RDCACHE */
    + (cap->issued & CEPH_CAP_FILE_CACHE) == 0 && /* but not before */
    + (__ceph_caps_issued(ci, NULL) & CEPH_CAP_FILE_CACHE) == 0) {
    + ci->i_rdcache_gen++;
    +
    + if (S_ISDIR(inode->i_mode)) {
    + dout(" marking %p NOT complete\n", inode);
    + ci->i_ceph_flags &= ~CEPH_I_COMPLETE;
    + }
    + }
    +
    + /*
    + * If CACHE is being revoked, and we have no dirty buffers,
    + * try to invalidate (once). (If there are dirty buffers, we
    + * will invalidate _after_ writeback.)
    + */
    + if (((cap->issued & ~newcaps) & CEPH_CAP_FILE_CACHE) &&
    + !ci->i_wrbuffer_ref && !tried_invalidate) {
    + dout("CACHE invalidation\n");
    + spin_unlock(&inode->i_lock);
    + tried_invalidate = 1;
    +
    + ret = invalidate_inode_pages2(&inode->i_data);
    + spin_lock(&inode->i_lock);
    + if (ret < 0) {
    + /* there were locked pages.. invalidate later
    + in a separate thread. */
    + if (ci->i_rdcache_revoking != ci->i_rdcache_gen) {
    + invalidate_async = 1;
    + ci->i_rdcache_revoking = ci->i_rdcache_gen;
    + }
    + } else {
    + /* we successfully invalidated those pages */
    + revoked_rdcache = 1;
    + ci->i_rdcache_gen = 0;
    + ci->i_rdcache_revoking = 0;
    + }
    + goto start;
    + }
    +
    + issued = __ceph_caps_issued(ci, &implemented);
    + issued |= implemented | __ceph_caps_dirty(ci);
    +
    + if ((issued & CEPH_CAP_AUTH_EXCL) == 0) {
    + inode->i_mode = le32_to_cpu(grant->mode);
    + inode->i_uid = le32_to_cpu(grant->uid);
    + inode->i_gid = le32_to_cpu(grant->gid);
    + dout("%p mode 0%o uid.gid %d.%d\n", inode, inode->i_mode,
    + inode->i_uid, inode->i_gid);
    + }
    +
    + if ((issued & CEPH_CAP_LINK_EXCL) == 0)
    + inode->i_nlink = le32_to_cpu(grant->nlink);
    +
    + if ((issued & CEPH_CAP_XATTR_EXCL) == 0 && grant->xattr_len) {
    + int len = le32_to_cpu(grant->xattr_len);
    + u64 version = le64_to_cpu(grant->xattr_version);
    +
    + if (!(len > 4 && *xattr_data == NULL) && /* ENOMEM in caller */
    + version > ci->i_xattrs.version) {
    + dout(" got new xattrs v%llu on %p len %d\n",
    + version, inode, len);
    + kfree(ci->i_xattrs.data);
    + ci->i_xattrs.len = len;
    + ci->i_xattrs.version = version;
    + ci->i_xattrs.data = *xattr_data;
    + *xattr_data = NULL;
    + }
    + }
    +
    + /* size/ctime/mtime/atime? */
    + ceph_fill_file_size(inode, issued,
    + le32_to_cpu(grant->truncate_seq),
    + le64_to_cpu(grant->truncate_size), size);
    + ceph_decode_timespec(&mtime, &grant->mtime);
    + ceph_decode_timespec(&atime, &grant->atime);
    + ceph_decode_timespec(&ctime, &grant->ctime);
    + ceph_fill_file_time(inode, issued,
    + le32_to_cpu(grant->time_warp_seq), &ctime, &mtime,
    + &atime);
    +
    + /* max size increase? */
    + if (max_size != ci->i_max_size) {
    + dout("max_size %lld -> %llu\n", ci->i_max_size, max_size);
    + ci->i_max_size = max_size;
    + if (max_size >= ci->i_wanted_max_size) {
    + ci->i_wanted_max_size = 0; /* reset */
    + ci->i_requested_max_size = 0;
    + }
    + wake = 1;
    + }
    +
    + /* check cap bits */
    + wanted = __ceph_caps_wanted(ci);
    + used = __ceph_caps_used(ci);
    + dirty = __ceph_caps_dirty(ci);
    + dout(" my wanted = %s, used = %s, dirty %s\n",
    + ceph_cap_string(wanted),
    + ceph_cap_string(used),
    + ceph_cap_string(dirty));
    + if (wanted != le32_to_cpu(grant->wanted)) {
    + dout("mds wanted %s -> %s\n",
    + ceph_cap_string(le32_to_cpu(grant->wanted)),
    + ceph_cap_string(wanted));
    + grant->wanted = cpu_to_le32(wanted);
    + }
    +
    + cap->seq = seq;
    +
    + /* file layout may have changed */
    + ci->i_layout = grant->layout;
    +
    + /* revocation, grant, or no-op? */
    + if (cap->issued & ~newcaps) {
    + dout("revocation: %s -> %s\n", ceph_cap_string(cap->issued),
    + ceph_cap_string(newcaps));
    + if ((used & ~newcaps) & CEPH_CAP_FILE_BUFFER) {
    + writeback = 1; /* will delay ack */
    + } else if (dirty & ~newcaps) {
    + reply = 2; /* initiate writeback in check_caps */
    + } else if (((used & ~newcaps) & CEPH_CAP_FILE_CACHE) == 0 ||
    + revoked_rdcache) {
    + /*
    + * we're not using revoked caps.. ack now.
    + * re-use incoming message.
    + */
    + cap->implemented = newcaps;
    + cap->mds_wanted = wanted;
    +
    + grant->size = cpu_to_le64(inode->i_size);
    + grant->max_size = 0; /* don't re-request */
    + ceph_encode_timespec(&grant->mtime, &inode->i_mtime);
    + ceph_encode_timespec(&grant->atime, &inode->i_atime);
    + grant->time_warp_seq = cpu_to_le32(ci->i_time_warp_seq);
    + grant->snap_follows =
    + cpu_to_le64(ci->i_snap_realm->cached_context->seq);
    + reply = 1;
    + wake = 1;
    + }
    + cap->issued = newcaps;
    + } else if (cap->issued == newcaps) {
    + dout("caps unchanged: %s -> %s\n",
    + ceph_cap_string(cap->issued), ceph_cap_string(newcaps));
    + } else {
    + dout("grant: %s -> %s\n", ceph_cap_string(cap->issued),
    + ceph_cap_string(newcaps));
    + cap->issued = newcaps;
    + cap->implemented |= newcaps; /* add bits only, to
    + * avoid stepping on a
    + * pending revocation */
    + wake = 1;
    + }
    +
    + spin_unlock(&inode->i_lock);
    + if (writeback) {
    + /*
    + * queue inode for writeback: we can't actually call
    + * filemap_write_and_wait, etc. from message handler
    + * context.
    + */
    + dout("queueing %p for writeback\n", inode);
    + if (ceph_queue_writeback(inode))
    + igrab(inode);
    + }
    + if (invalidate_async) {
    + dout("queueing %p for page invalidation\n", inode);
    + if (ceph_queue_page_invalidation(inode))
    + igrab(inode);
    + }
    + if (wake)
    + wake_up(&ci->i_cap_wq);
    + return reply;
    +}
    +
    +/*
    + * Handle FLUSH_ACK from MDS, indicating that metadata we sent to the
    + * MDS has been safely committed.
    + */
    +static void handle_cap_flush_ack(struct inode *inode,
    + struct ceph_mds_caps *m,
    + struct ceph_mds_session *session,
    + struct ceph_cap *cap)
    + __releases(inode->i_lock)
    +{
    + struct ceph_inode_info *ci = ceph_inode(inode);
    + struct ceph_mds_client *mdsc = &ceph_client(inode->i_sb)->mdsc;
    + unsigned seq = le32_to_cpu(m->seq);
    + int dirty = le32_to_cpu(m->dirty);
    + int cleaned = 0;
    + u64 flush_tid = le64_to_cpu(m->client_tid);
    + int old_dirty = 0, new_dirty = 0;
    + int i;
    +
    + for (i = 0; i < CEPH_CAP_BITS; i++)
    + if ((dirty & (1 << i)) &&
    + flush_tid == ci->i_cap_flush_tid[i])
    + cleaned |= 1 << i;
    +
    + dout("handle_cap_flush_ack inode %p mds%d seq %d on %s cleaned %s,"
    + " flushing %s -> %s\n",
    + inode, session->s_mds, seq, ceph_cap_string(dirty),
    + ceph_cap_string(cleaned), ceph_cap_string(ci->i_flushing_caps),
    + ceph_cap_string(ci->i_flushing_caps & ~cleaned));
    +
    + if (ci->i_flushing_caps == (ci->i_flushing_caps & ~cleaned))
    + goto out;
    +
    + old_dirty = ci->i_dirty_caps | ci->i_flushing_caps;
    + ci->i_flushing_caps &= ~cleaned;
    + new_dirty = ci->i_dirty_caps | ci->i_flushing_caps;
    +
    + spin_lock(&mdsc->cap_dirty_lock);
    + if (ci->i_flushing_caps == 0) {
    + list_del_init(&ci->i_flushing_item);
    + if (!list_empty(&session->s_cap_flushing))
    + dout(" mds%d still flushing cap on %p\n",
    + session->s_mds,
    + &list_entry(session->s_cap_flushing.next,
    + struct ceph_inode_info,
    + i_flushing_item)->vfs_inode);
    + mdsc->num_cap_flushing--;
    + wake_up(&mdsc->cap_flushing_wq);
    + dout(" inode %p now !flushing\n", inode);
    + }
    + if (old_dirty && !new_dirty) {
    + dout(" inode %p now clean\n", inode);
    + list_del_init(&ci->i_dirty_item);
    + }
    + spin_unlock(&mdsc->cap_dirty_lock);
    + wake_up(&ci->i_cap_wq);
    +
    +out:
    + spin_unlock(&inode->i_lock);
    + if (old_dirty && !new_dirty)
    + iput(inode);
    +}
    +
    +/*
    + * Handle FLUSHSNAP_ACK. MDS has flushed snap data to disk and we can
    + * throw away our cap_snap.
    + *
    + * Caller hold s_mutex.
    + */
    +static void handle_cap_flushsnap_ack(struct inode *inode,
    + struct ceph_mds_caps *m,
    + struct ceph_mds_session *session)
    +{
    + struct ceph_inode_info *ci = ceph_inode(inode);
    + u64 follows = le64_to_cpu(m->snap_follows);
    + u64 flush_tid = le64_to_cpu(m->client_tid);
    + struct ceph_cap_snap *capsnap;
    + int drop = 0;
    +
    + dout("handle_cap_flushsnap_ack inode %p ci %p mds%d follows %lld\n",
    + inode, ci, session->s_mds, follows);
    +
    + spin_lock(&inode->i_lock);
    + list_for_each_entry(capsnap, &ci->i_cap_snaps, ci_item) {
    + if (capsnap->follows == follows) {
    + if (capsnap->flush_tid != flush_tid) {
    + dout(" cap_snap %p follows %lld tid %lld !="
    + " %lld\n", capsnap, follows,
    + flush_tid, capsnap->flush_tid);
    + break;
    + }
    + WARN_ON(capsnap->dirty_pages || capsnap->writing);
    + dout(" removing cap_snap %p follows %lld\n",
    + capsnap, follows);
    + ceph_put_snap_context(capsnap->context);
    + list_del(&capsnap->ci_item);
    + list_del(&capsnap->flushing_item);
    + ceph_put_cap_snap(capsnap);
    + drop = 1;
    + break;
    + } else {
    + dout(" skipping cap_snap %p follows %lld\n",
    + capsnap, capsnap->follows);
    + }
    + }
    + spin_unlock(&inode->i_lock);
    + if (drop)
    + iput(inode);
    +}
    +
    +/*
    + * Handle TRUNC from MDS, indicating file truncation.
    + *
    + * caller hold s_mutex.
    + */
    +static void handle_cap_trunc(struct inode *inode,
    + struct ceph_mds_caps *trunc,
    + struct ceph_mds_session *session)
    + __releases(inode->i_lock)
    +{
    + struct ceph_inode_info *ci = ceph_inode(inode);
    + int mds = session->s_mds;
    + int seq = le32_to_cpu(trunc->seq);
    + u32 truncate_seq = le32_to_cpu(trunc->truncate_seq);
    + u64 truncate_size = le64_to_cpu(trunc->truncate_size);
    + u64 size = le64_to_cpu(trunc->size);
    + int implemented = 0;
    + int dirty = __ceph_caps_dirty(ci);
    + int issued = __ceph_caps_issued(ceph_inode(inode), &implemented);
    + int queue_trunc = 0;
    +
    + issued |= implemented | dirty;
    +
    + dout("handle_cap_trunc inode %p mds%d seq %d to %lld seq %d\n",
    + inode, mds, seq, truncate_size, truncate_seq);
    + queue_trunc = ceph_fill_file_size(inode, issued,
    + truncate_seq, truncate_size, size);
    + spin_unlock(&inode->i_lock);
    +
    + if (queue_trunc)
    + if (queue_work(ceph_client(inode->i_sb)->trunc_wq,
    + &ci->i_vmtruncate_work))
    + igrab(inode);
    +}
    +
    +/*
    + * Handle EXPORT from MDS. Cap is being migrated _from_ this mds to a
    + * different one. If we are the most recent migration we've seen (as
    + * indicated by mseq), make note of the migrating cap bits for the
    + * duration (until we see the corresponding IMPORT).
    + *
    + * caller holds s_mutex
    + */
    +static void handle_cap_export(struct inode *inode, struct ceph_mds_caps *ex,
    + struct ceph_mds_session *session)
    +{
    + struct ceph_inode_info *ci = ceph_inode(inode);
    + int mds = session->s_mds;
    + unsigned mseq = le32_to_cpu(ex->migrate_seq);
    + struct ceph_cap *cap = NULL, *t;
    + struct rb_node *p;
    + int remember = 1;
    +
    + dout("handle_cap_export inode %p ci %p mds%d mseq %d\n",
    + inode, ci, mds, mseq);
    +
    + spin_lock(&inode->i_lock);
    +
    + /* make sure we haven't seen a higher mseq */
    + for (p = rb_first(&ci->i_caps); p; p = rb_next(p)) {
    + t = rb_entry(p, struct ceph_cap, ci_node);
    + if (ceph_seq_cmp(t->mseq, mseq) > 0) {
    + dout(" higher mseq on cap from mds%d\n",
    + t->session->s_mds);
    + remember = 0;
    + }
    + if (t->session->s_mds == mds)
    + cap = t;
    + }
    +
    + if (cap) {
    + if (remember) {
    + /* make note */
    + ci->i_cap_exporting_mds = mds;
    + ci->i_cap_exporting_mseq = mseq;
    + ci->i_cap_exporting_issued = cap->issued;
    + }
    + __ceph_remove_cap(cap, NULL);
    + } else {
    + WARN_ON(!cap);
    + }
    +
    + spin_unlock(&inode->i_lock);
    +}
    +
    +/*
    + * Handle cap IMPORT. If there are temp bits from an older EXPORT,
    + * clean them up.
    + *
    + * caller holds s_mutex.
    + */
    +static void handle_cap_import(struct ceph_mds_client *mdsc,
    + struct inode *inode, struct ceph_mds_caps *im,
    + struct ceph_mds_session *session,
    + void *snaptrace, int snaptrace_len)
    +{
    + struct ceph_inode_info *ci = ceph_inode(inode);
    + int mds = session->s_mds;
    + unsigned issued = le32_to_cpu(im->caps);
    + unsigned wanted = le32_to_cpu(im->wanted);
    + unsigned seq = le32_to_cpu(im->seq);
    + unsigned mseq = le32_to_cpu(im->migrate_seq);
    + u64 realmino = le64_to_cpu(im->realm);
    + unsigned long ttl_ms = le32_to_cpu(im->ttl_ms);
    + u64 cap_id = le64_to_cpu(im->cap_id);
    +
    + if (ci->i_cap_exporting_mds >= 0 &&
    + ceph_seq_cmp(ci->i_cap_exporting_mseq, mseq) < 0) {
    + dout("handle_cap_import inode %p ci %p mds%d mseq %d"
    + " - cleared exporting from mds%d\n",
    + inode, ci, mds, mseq,
    + ci->i_cap_exporting_mds);
    + ci->i_cap_exporting_issued = 0;
    + ci->i_cap_exporting_mseq = 0;
    + ci->i_cap_exporting_mds = -1;
    + } else {
    + dout("handle_cap_import inode %p ci %p mds%d mseq %d\n",
    + inode, ci, mds, mseq);
    + }
    +
    + down_write(&mdsc->snap_rwsem);
    + ceph_update_snap_trace(mdsc, snaptrace, snaptrace+snaptrace_len,
    + false);
    + downgrade_write(&mdsc->snap_rwsem);
    + ceph_add_cap(inode, session, cap_id, -1,
    + issued, wanted, seq, mseq, realmino,
    + ttl_ms, jiffies - ttl_ms/2, CEPH_CAP_FLAG_AUTH,
    + NULL /* no caps context */);
    + try_flush_caps(inode, session, NULL);
    + up_read(&mdsc->snap_rwsem);
    +}
    +
    +/*
    + * Handle a caps message from the MDS.
    + *
    + * Identify the appropriate session, inode, and call the right handler
    + * based on the cap op.
    + */
    +void ceph_handle_caps(struct ceph_mds_client *mdsc,
    + struct ceph_msg *msg)
    +{
    + struct super_block *sb = mdsc->client->sb;
    + struct ceph_mds_session *session;
    + struct inode *inode;
    + struct ceph_cap *cap;
    + struct ceph_mds_caps *h;
    + int mds = le32_to_cpu(msg->hdr.src.name.num);
    + int op;
    + u32 seq;
    + struct ceph_vino vino;
    + u64 cap_id;
    + u64 size, max_size;
    + int check_caps = 0;
    + void *xattr_data = NULL;
    + int r;
    +
    + dout("handle_caps from mds%d\n", mds);
    +
    + /* decode */
    + if (msg->front.iov_len < sizeof(*h))
    + goto bad;
    + h = msg->front.iov_base;
    + op = le32_to_cpu(h->op);
    + vino.ino = le64_to_cpu(h->ino);
    + vino.snap = CEPH_NOSNAP;
    + cap_id = le64_to_cpu(h->cap_id);
    + seq = le32_to_cpu(h->seq);
    + size = le64_to_cpu(h->size);
    + max_size = le64_to_cpu(h->max_size);
    +
    + /* find session */
    + mutex_lock(&mdsc->mutex);
    + session = __ceph_lookup_mds_session(mdsc, mds);
    + mutex_unlock(&mdsc->mutex);
    + if (!session) {
    + dout("WTF, got cap but no session for mds%d\n", mds);
    + return;
    + }
    +
    + mutex_lock(&session->s_mutex);
    + session->s_seq++;
    + dout(" mds%d seq %lld\n", session->s_mds, session->s_seq);
    +
    + /* lookup ino */
    + inode = ceph_find_inode(sb, vino);
    + dout(" op %s ino %llx inode %p\n", ceph_cap_op_name(op), vino.ino,
    + inode);
    + if (!inode) {
    + dout(" i don't have ino %llx\n", vino.ino);
    + goto done;
    + }
    +
    + /* these will work even if we don't have a cap yet */
    + switch (op) {
    + case CEPH_CAP_OP_FLUSHSNAP_ACK:
    + handle_cap_flushsnap_ack(inode, h, session);
    + goto done;
    +
    + case CEPH_CAP_OP_EXPORT:
    + handle_cap_export(inode, h, session);
    + goto done;
    +
    + case CEPH_CAP_OP_IMPORT:
    + handle_cap_import(mdsc, inode, h, session,
    + msg->front.iov_base + sizeof(*h),
    + le32_to_cpu(h->snap_trace_len));
    + check_caps = 1; /* we may have sent a RELEASE to the old auth */
    + goto done;
    + }
    +
    + /* preallocate space for xattrs? */
    + if (le32_to_cpu(h->xattr_len) > 4)
    + xattr_data = kmalloc(le32_to_cpu(h->xattr_len), GFP_NOFS);
    +
    + /* the rest require a cap */
    + spin_lock(&inode->i_lock);
    + cap = __get_cap_for_mds(ceph_inode(inode), mds);
    + if (!cap) {
    + dout("no cap on %p ino %llx.%llx from mds%d, releasing\n",
    + inode, ceph_ino(inode), ceph_snap(inode), mds);
    + spin_unlock(&inode->i_lock);
    + goto done;
    + }
    +
    + /* note that each of these drops i_lock for us */
    + switch (op) {
    + case CEPH_CAP_OP_REVOKE:
    + case CEPH_CAP_OP_GRANT:
    + r = handle_cap_grant(inode, h, session, cap, &xattr_data);
    + if (r == 1) {
    + dout(" sending reply back to mds%d\n", mds);
    + ceph_msg_get(msg);
    + ceph_send_msg_mds(mdsc, msg, mds);
    + } else if (r == 2) {
    + ceph_check_caps(ceph_inode(inode),
    + CHECK_CAPS_NODELAY|CHECK_CAPS_AUTHONLY,
    + session);
    + }
    + break;
    +
    + case CEPH_CAP_OP_FLUSH_ACK:
    + handle_cap_flush_ack(inode, h, session, cap);
    + break;
    +
    + case CEPH_CAP_OP_TRUNC:
    + handle_cap_trunc(inode, h, session);
    + break;
    +
    + default:
    + spin_unlock(&inode->i_lock);
    + pr_err("ceph_handle_caps: unknown cap op %d %s\n", op,
    + ceph_cap_op_name(op));
    + }
    +
    +done:
    + mutex_unlock(&session->s_mutex);
    + ceph_put_mds_session(session);
    +
    + kfree(xattr_data);
    + if (check_caps)
    + ceph_check_caps(ceph_inode(inode), CHECK_CAPS_NODELAY, NULL);
    + if (inode)
    + iput(inode);
    + return;
    +
    +bad:
    + pr_err("ceph_handle_caps: corrupt message\n");
    + return;
    +}
    +
    +/*
    + * Delayed work handler to process end of delayed cap release LRU list.
    + */
    +void ceph_check_delayed_caps(struct ceph_mds_client *mdsc, int flushdirty)
    +{
    + struct ceph_inode_info *ci;
    + int flags = CHECK_CAPS_NODELAY;
    +
    + if (flushdirty)
    + flags |= CHECK_CAPS_FLUSH;
    +
    + dout("check_delayed_caps\n");
    + while (1) {
    + spin_lock(&mdsc->cap_delay_lock);
    + if (list_empty(&mdsc->cap_delay_list))
    + break;
    + ci = list_first_entry(&mdsc->cap_delay_list,
    + struct ceph_inode_info,
    + i_cap_delay_list);
    + if ((ci->i_ceph_flags & CEPH_I_FLUSH) == 0 &&
    + time_before(jiffies, ci->i_hold_caps_max))
    + break;
    + list_del_init(&ci->i_cap_delay_list);
    + spin_unlock(&mdsc->cap_delay_lock);
    + dout("check_delayed_caps on %p\n", &ci->vfs_inode);
    + ceph_check_caps(ci, flags, NULL);
    + }
    + spin_unlock(&mdsc->cap_delay_lock);
    +}
    +
    +/*
    + * Drop open file reference. If we were the last open file,
    + * we may need to release capabilities to the MDS (or schedule
    + * their delayed release).
    + */
    +void ceph_put_fmode(struct ceph_inode_info *ci, int fmode)
    +{
    + struct inode *inode = &ci->vfs_inode;
    + int last = 0;
    +
    + spin_lock(&inode->i_lock);
    + dout("put_fmode %p fmode %d %d -> %d\n", inode, fmode,
    + ci->i_nr_by_mode[fmode], ci->i_nr_by_mode[fmode]-1);
    + BUG_ON(ci->i_nr_by_mode[fmode] == 0);
    + if (--ci->i_nr_by_mode[fmode] == 0)
    + last++;
    + spin_unlock(&inode->i_lock);
    +
    + if (last && ci->i_vino.snap == CEPH_NOSNAP)
    + ceph_check_caps(ci, 0, NULL);
    +}
    +
    +/*
    + * Helpers for embedding cap and dentry lease releases into mds
    + * requests.
    + */
    +int ceph_encode_inode_release(void **p, struct inode *inode,
    + int mds, int drop, int unless, int force)
    +{
    + struct ceph_inode_info *ci = ceph_inode(inode);
    + struct ceph_cap *cap;
    + struct ceph_mds_request_release *rel = *p;
    + int ret = 0;
    +
    + dout("encode_inode_release %p mds%d drop %s unless %s\n", inode,
    + mds, ceph_cap_string(drop), ceph_cap_string(unless));
    +
    + spin_lock(&inode->i_lock);
    + cap = __get_cap_for_mds(ci, mds);
    + if (cap && __cap_is_valid(cap)) {
    + if (force ||
    + ((cap->issued & drop) &&
    + (cap->issued & unless) == 0)) {
    + if ((cap->issued & drop) &&
    + (cap->issued & unless) == 0) {
    + dout("encode_inode_release %p cap %p %s -> "
    + "%s\n", inode, cap,
    + ceph_cap_string(cap->issued),
    + ceph_cap_string(cap->issued & ~drop));
    + cap->issued &= ~drop;
    + cap->implemented &= ~drop;
    + if (ci->i_ceph_flags & CEPH_I_NODELAY) {
    + int wanted = __ceph_caps_wanted(ci);
    + dout(" wanted %s -> %s (act %s)\n",
    + ceph_cap_string(cap->mds_wanted),
    + ceph_cap_string(cap->mds_wanted &
    + ~wanted),
    + ceph_cap_string(wanted));
    + cap->mds_wanted &= wanted;
    + }
    + } else {
    + dout("encode_inode_release %p cap %p %s"
    + " (force)\n", inode, cap,
    + ceph_cap_string(cap->issued));
    + }
    +
    + rel->ino = cpu_to_le64(ceph_ino(inode));
    + rel->cap_id = cpu_to_le64(cap->cap_id);
    + rel->seq = cpu_to_le32(cap->seq);
    + rel->issue_seq = cpu_to_le32(cap->issue_seq),
    + rel->mseq = cpu_to_le32(cap->mseq);
    + rel->caps = cpu_to_le32(cap->issued);
    + rel->wanted = cpu_to_le32(cap->mds_wanted);
    + rel->dname_len = 0;
    + rel->dname_seq = 0;
    + *p += sizeof(*rel);
    + ret = 1;
    + } else {
    + dout("encode_inode_release %p cap %p %s\n",
    + inode, cap, ceph_cap_string(cap->issued));
    + }
    + }
    + spin_unlock(&inode->i_lock);
    + return ret;
    +}
    +
    +int ceph_encode_dentry_release(void **p, struct dentry *dentry,
    + int mds, int drop, int unless)
    +{
    + struct inode *dir = dentry->d_parent->d_inode;
    + struct ceph_mds_request_release *rel = *p;
    + struct ceph_dentry_info *di = ceph_dentry(dentry);
    + int ret;
    +
    + ret = ceph_encode_inode_release(p, dir, mds, drop, unless, 1);
    +
    + /* drop dentry lease too? */
    + spin_lock(&dentry->d_lock);
    + if (ret && di->lease_session && di->lease_session->s_mds == mds) {
    + dout("encode_dentry_release %p mds%d seq %d\n",
    + dentry, mds, (int)di->lease_seq);
    + rel->dname_len = cpu_to_le32(dentry->d_name.len);
    + memcpy(*p, dentry->d_name.name, dentry->d_name.len);
    + *p += dentry->d_name.len;
    + rel->dname_seq = cpu_to_le32(di->lease_seq);
    + }
    + spin_unlock(&dentry->d_lock);
    + return ret;
    +}
    --
    1.5.6.5


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      Last update: 2009-08-06 00:35    [W:0.202 / U:0.392 seconds]
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