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Subject[patch 13/27] fs: scale inode alias list
Add a new lock, dcache_inode_lock, to protect the inode's i_dentry list
from concurrent modification. d_alias is also protected by d_lock.

---
fs/affs/amigaffs.c | 2 +
fs/dcache.c | 56 +++++++++++++++++++++++++++++++++++++++-----
fs/exportfs/expfs.c | 4 +++
fs/nfs/getroot.c | 4 +++
fs/notify/inotify/inotify.c | 2 +
fs/ocfs2/dcache.c | 3 +-
fs/sysfs/dir.c | 3 ++
include/linux/dcache.h | 1
8 files changed, 68 insertions(+), 7 deletions(-)
Index: linux-2.6/fs/dcache.c
===================================================================
--- linux-2.6.orig/fs/dcache.c
+++ linux-2.6/fs/dcache.c
@@ -36,6 +36,8 @@

/*
* Usage:
+ * dcache_inode_lock protects:
+ * - the inode alias lists, d_inode
* dcache_hash_lock protects:
* - the dcache hash table
* dcache_lru_lock protects:
@@ -49,18 +51,21 @@
*
* Ordering:
* dcache_lock
- * dentry->d_lock
- * dcache_lru_lock
- * dcache_hash_lock
+ * dcache_inode_lock
+ * dentry->d_lock
+ * dcache_lru_lock
+ * dcache_hash_lock
*/
int sysctl_vfs_cache_pressure __read_mostly = 100;
EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure);

+__cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_inode_lock);
__cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_hash_lock);
__cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lru_lock);
__cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lock);
__cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock);

+EXPORT_SYMBOL(dcache_inode_lock);
EXPORT_SYMBOL(dcache_hash_lock);
EXPORT_SYMBOL(dcache_lock);

@@ -125,6 +130,7 @@ static void d_free(struct dentry *dentry
*/
static void dentry_iput(struct dentry * dentry)
__releases(dentry->d_lock)
+ __releases(dcache_inode_lock)
__releases(dcache_lock)
{
struct inode *inode = dentry->d_inode;
@@ -132,6 +138,7 @@ static void dentry_iput(struct dentry *
dentry->d_inode = NULL;
list_del_init(&dentry->d_alias);
spin_unlock(&dentry->d_lock);
+ spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
if (!inode->i_nlink)
fsnotify_inoderemove(inode);
@@ -141,6 +148,7 @@ static void dentry_iput(struct dentry *
iput(inode);
} else {
spin_unlock(&dentry->d_lock);
+ spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
}
}
@@ -212,6 +220,7 @@ static void dentry_lru_del_init(struct d
*/
static struct dentry *d_kill(struct dentry *dentry)
__releases(dentry->d_lock)
+ __releases(dcache_inode_lock)
__releases(dcache_lock)
{
struct dentry *parent;
@@ -276,16 +285,21 @@ repeat:
* want to reduce dcache_lock anyway so this will
* get improved.
*/
+drop1:
spin_unlock(&dentry->d_lock);
goto repeat;
}
+ if (!spin_trylock(&dcache_inode_lock)) {
+drop2:
+ spin_unlock(&dcache_lock);
+ goto drop1;
+ }
parent = dentry->d_parent;
if (parent) {
BUG_ON(parent == dentry);
if (!spin_trylock(&parent->d_lock)) {
- spin_unlock(&dentry->d_lock);
- spin_unlock(&dcache_lock);
- goto repeat;
+ spin_unlock(&dcache_inode_lock);
+ goto drop2;
}
}
}
@@ -313,6 +327,7 @@ repeat:
spin_unlock(&dentry->d_lock);
if (parent)
spin_unlock(&parent->d_lock);
+ spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
return;

@@ -487,7 +502,9 @@ struct dentry * d_find_alias(struct inod

if (!list_empty(&inode->i_dentry)) {
spin_lock(&dcache_lock);
+ spin_lock(&dcache_inode_lock);
de = __d_find_alias(inode, 0);
+ spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
}
return de;
@@ -502,18 +519,21 @@ void d_prune_aliases(struct inode *inode
struct dentry *dentry;
restart:
spin_lock(&dcache_lock);
+ spin_lock(&dcache_inode_lock);
list_for_each_entry(dentry, &inode->i_dentry, d_alias) {
spin_lock(&dentry->d_lock);
if (!dentry->d_count) {
__dget_locked_dlock(dentry);
__d_drop(dentry);
spin_unlock(&dentry->d_lock);
+ spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
dput(dentry);
goto restart;
}
spin_unlock(&dentry->d_lock);
}
+ spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
}

@@ -541,6 +561,7 @@ static void prune_one_dentry(struct dent
struct dentry *parent = NULL;

spin_lock(&dcache_lock);
+ spin_lock(&dcache_inode_lock);
again:
spin_lock(&dentry->d_lock);
if (dentry->d_parent && dentry != dentry->d_parent) {
@@ -555,6 +576,7 @@ again:
if (parent)
spin_unlock(&parent->d_lock);
spin_unlock(&dentry->d_lock);
+ spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
return;
}
@@ -625,6 +647,7 @@ restart:
spin_unlock(&dcache_lru_lock);

spin_lock(&dcache_lock);
+ spin_lock(&dcache_inode_lock);
again:
spin_lock(&dcache_lru_lock); /* lru_lock also protects tmp list */
while (!list_empty(&tmp)) {
@@ -657,8 +680,10 @@ again1:
prune_one_dentry(dentry);
/* dcache_lock and dentry->d_lock dropped */
spin_lock(&dcache_lock);
+ spin_lock(&dcache_inode_lock);
spin_lock(&dcache_lru_lock);
}
+ spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);

if (count == NULL && !list_empty(&sb->s_dentry_lru))
@@ -1195,7 +1220,9 @@ void d_instantiate(struct dentry *entry,
{
BUG_ON(!list_empty(&entry->d_alias));
spin_lock(&dcache_lock);
+ spin_lock(&dcache_inode_lock);
__d_instantiate(entry, inode);
+ spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
security_d_instantiate(entry, inode);
}
@@ -1255,7 +1282,9 @@ struct dentry *d_instantiate_unique(stru
BUG_ON(!list_empty(&entry->d_alias));

spin_lock(&dcache_lock);
+ spin_lock(&dcache_inode_lock);
result = __d_instantiate_unique(entry, inode);
+ spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);

if (!result) {
@@ -1345,8 +1374,10 @@ struct dentry *d_obtain_alias(struct ino
tmp->d_parent = tmp; /* make sure dput doesn't croak */

spin_lock(&dcache_lock);
+ spin_lock(&dcache_inode_lock);
res = __d_find_alias(inode, 0);
if (res) {
+ spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
dput(tmp);
goto out_iput;
@@ -1361,6 +1392,7 @@ struct dentry *d_obtain_alias(struct ino
list_add(&tmp->d_alias, &inode->i_dentry);
hlist_add_head(&tmp->d_hash, &inode->i_sb->s_anon);
spin_unlock(&tmp->d_lock);
+ spin_unlock(&dcache_inode_lock);

spin_unlock(&dcache_lock);
return tmp;
@@ -1393,9 +1425,11 @@ struct dentry *d_splice_alias(struct ino

if (inode && S_ISDIR(inode->i_mode)) {
spin_lock(&dcache_lock);
+ spin_lock(&dcache_inode_lock);
new = __d_find_alias(inode, 1);
if (new) {
BUG_ON(!(new->d_flags & DCACHE_DISCONNECTED));
+ spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
security_d_instantiate(new, inode);
d_rehash(dentry);
@@ -1404,6 +1438,7 @@ struct dentry *d_splice_alias(struct ino
} else {
/* already taking dcache_lock, so d_add() by hand */
__d_instantiate(dentry, inode);
+ spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
security_d_instantiate(dentry, inode);
d_rehash(dentry);
@@ -1477,8 +1512,10 @@ struct dentry *d_add_ci(struct dentry *d
* already has a dentry.
*/
spin_lock(&dcache_lock);
+ spin_lock(&dcache_inode_lock);
if (!S_ISDIR(inode->i_mode) || list_empty(&inode->i_dentry)) {
__d_instantiate(found, inode);
+ spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
security_d_instantiate(found, inode);
return found;
@@ -1490,6 +1527,7 @@ struct dentry *d_add_ci(struct dentry *d
*/
new = list_entry(inode->i_dentry.next, struct dentry, d_alias);
dget_locked(new);
+ spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
security_d_instantiate(found, inode);
d_move(new, found);
@@ -1705,6 +1743,7 @@ void d_delete(struct dentry * dentry)
* Are we the only user?
*/
spin_lock(&dcache_lock);
+ spin_lock(&dcache_inode_lock);
spin_lock(&dentry->d_lock);
isdir = S_ISDIR(dentry->d_inode->i_mode);
if (dentry->d_count == 1) {
@@ -1717,6 +1756,7 @@ void d_delete(struct dentry * dentry)
__d_drop(dentry);

spin_unlock(&dentry->d_lock);
+ spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);

fsnotify_nameremove(dentry, isdir);
@@ -1963,6 +2003,7 @@ out_unalias:
d_move_locked(alias, dentry);
ret = alias;
out_err:
+ spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
if (m2)
mutex_unlock(m2);
@@ -2028,6 +2069,7 @@ struct dentry *d_materialise_unique(stru
BUG_ON(!d_unhashed(dentry));

spin_lock(&dcache_lock);
+ spin_lock(&dcache_inode_lock);

if (!inode) {
actual = dentry;
@@ -2072,6 +2114,7 @@ found:
_d_rehash(actual);
spin_unlock(&dcache_hash_lock);
spin_unlock(&actual->d_lock);
+ spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
out_nolock:
if (actual == dentry) {
@@ -2083,6 +2126,7 @@ out_nolock:
return actual;

shouldnt_be_hashed:
+ spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
BUG();
}
Index: linux-2.6/fs/sysfs/dir.c
===================================================================
--- linux-2.6.orig/fs/sysfs/dir.c
+++ linux-2.6/fs/sysfs/dir.c
@@ -548,6 +548,7 @@ static void sysfs_drop_dentry(struct sys
*/
repeat:
spin_lock(&dcache_lock);
+ spin_lock(&dcache_inode_lock);
list_for_each_entry(dentry, &inode->i_dentry, d_alias) {
spin_lock(&dentry->d_lock);
if (d_unhashed(dentry)) {
@@ -557,10 +558,12 @@ repeat:
dget_locked_dlock(dentry);
__d_drop(dentry);
spin_unlock(&dentry->d_lock);
+ spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
dput(dentry);
goto repeat;
}
+ spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);

/* adjust nlink and update timestamp */
Index: linux-2.6/include/linux/dcache.h
===================================================================
--- linux-2.6.orig/include/linux/dcache.h
+++ linux-2.6/include/linux/dcache.h
@@ -184,6 +184,7 @@ d_iput: no no no yes

#define DCACHE_COOKIE 0x0040 /* For use by dcookie subsystem */

+extern spinlock_t dcache_inode_lock;
extern spinlock_t dcache_hash_lock;
extern spinlock_t dcache_lock;
extern seqlock_t rename_lock;
Index: linux-2.6/fs/notify/inotify/inotify.c
===================================================================
--- linux-2.6.orig/fs/notify/inotify/inotify.c
+++ linux-2.6/fs/notify/inotify/inotify.c
@@ -185,6 +185,7 @@ static void set_dentry_child_flags(struc
struct dentry *alias;

spin_lock(&dcache_lock);
+ spin_lock(&dcache_inode_lock);
list_for_each_entry(alias, &inode->i_dentry, d_alias) {
struct dentry *child;

@@ -202,6 +203,7 @@ static void set_dentry_child_flags(struc
}
spin_unlock(&alias->d_lock);
}
+ spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
}

Index: linux-2.6/fs/exportfs/expfs.c
===================================================================
--- linux-2.6.orig/fs/exportfs/expfs.c
+++ linux-2.6/fs/exportfs/expfs.c
@@ -48,8 +48,10 @@ find_acceptable_alias(struct dentry *res
return result;

spin_lock(&dcache_lock);
+ spin_lock(&dcache_inode_lock);
list_for_each_entry(dentry, &result->d_inode->i_dentry, d_alias) {
dget_locked(dentry);
+ spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
if (toput)
dput(toput);
@@ -58,8 +60,10 @@ find_acceptable_alias(struct dentry *res
return dentry;
}
spin_lock(&dcache_lock);
+ spin_lock(&dcache_inode_lock);
toput = dentry;
}
+ spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);

if (toput)
Index: linux-2.6/fs/affs/amigaffs.c
===================================================================
--- linux-2.6.orig/fs/affs/amigaffs.c
+++ linux-2.6/fs/affs/amigaffs.c
@@ -129,6 +129,7 @@ affs_fix_dcache(struct dentry *dentry, u
struct list_head *head, *next;

spin_lock(&dcache_lock);
+ spin_lock(&dcache_inode_lock);
head = &inode->i_dentry;
next = head->next;
while (next != head) {
@@ -139,6 +140,7 @@ affs_fix_dcache(struct dentry *dentry, u
}
next = next->next;
}
+ spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
}

Index: linux-2.6/fs/ocfs2/dcache.c
===================================================================
--- linux-2.6.orig/fs/ocfs2/dcache.c
+++ linux-2.6/fs/ocfs2/dcache.c
@@ -141,7 +141,7 @@ struct dentry *ocfs2_find_local_alias(st
struct dentry *dentry = NULL;

spin_lock(&dcache_lock);
-
+ spin_lock(&dcache_inode_lock);
list_for_each(p, &inode->i_dentry) {
dentry = list_entry(p, struct dentry, d_alias);

@@ -159,6 +159,7 @@ struct dentry *ocfs2_find_local_alias(st
dentry = NULL;
}

+ spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);

return dentry;
Index: linux-2.6/fs/nfs/getroot.c
===================================================================
--- linux-2.6.orig/fs/nfs/getroot.c
+++ linux-2.6/fs/nfs/getroot.c
@@ -66,7 +66,11 @@ static int nfs_superblock_set_dummy_root
* Oops, since the test for IS_ROOT() will fail.
*/
spin_lock(&dcache_lock);
+ spin_lock(&dcache_inode_lock);
+ spin_lock(&sb->s_root->d_lock);
list_del_init(&sb->s_root->d_alias);
+ spin_unlock(&sb->s_root->d_lock);
+ spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
}
return 0;



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