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    Subject[RFC][PATCH v4 25/69] finally fold get_link() into pick_link()
    Date
    From: Al Viro <viro@zeniv.linux.org.uk>

    kill nd->link_inode, while we are at it

    Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
    ---
    fs/namei.c | 135 ++++++++++++++++++++++++++++---------------------------------
    1 file changed, 61 insertions(+), 74 deletions(-)

    diff --git a/fs/namei.c b/fs/namei.c
    index 969b99a88631..9b08c64397c8 100644
    --- a/fs/namei.c
    +++ b/fs/namei.c
    @@ -503,7 +503,6 @@ struct nameidata {
    } *stack, internal[EMBEDDED_LEVELS];
    struct filename *name;
    struct nameidata *saved;
    - struct inode *link_inode;
    unsigned root_seq;
    int dfd;
    } __randomize_layout;
    @@ -962,9 +961,8 @@ int sysctl_protected_regular __read_mostly;
    *
    * Returns 0 if following the symlink is allowed, -ve on error.
    */
    -static inline int may_follow_link(struct nameidata *nd)
    +static inline int may_follow_link(struct nameidata *nd, const struct inode *inode)
    {
    - const struct inode *inode;
    const struct inode *parent;
    kuid_t puid;

    @@ -972,7 +970,6 @@ static inline int may_follow_link(struct nameidata *nd)
    return 0;

    /* Allowed if owner and follower match. */
    - inode = nd->link_inode;
    if (uid_eq(current_cred()->fsuid, inode->i_uid))
    return 0;

    @@ -1106,73 +1103,6 @@ static int may_create_in_sticky(umode_t dir_mode, kuid_t dir_uid,
    return 0;
    }

    -static __always_inline
    -const char *get_link(struct nameidata *nd)
    -{
    - struct saved *last = nd->stack + nd->depth - 1;
    - struct dentry *dentry = last->link.dentry;
    - struct inode *inode = nd->link_inode;
    - int error;
    - const char *res;
    -
    - if (!(nd->flags & LOOKUP_PARENT)) {
    - error = may_follow_link(nd);
    - if (unlikely(error))
    - return ERR_PTR(error);
    - }
    -
    - if (unlikely(nd->flags & LOOKUP_NO_SYMLINKS))
    - return ERR_PTR(-ELOOP);
    -
    - if (!(nd->flags & LOOKUP_RCU)) {
    - touch_atime(&last->link);
    - cond_resched();
    - } else if (atime_needs_update(&last->link, inode)) {
    - if (unlikely(unlazy_walk(nd)))
    - return ERR_PTR(-ECHILD);
    - touch_atime(&last->link);
    - }
    -
    - error = security_inode_follow_link(dentry, inode,
    - nd->flags & LOOKUP_RCU);
    - if (unlikely(error))
    - return ERR_PTR(error);
    -
    - nd->last_type = LAST_BIND;
    - res = READ_ONCE(inode->i_link);
    - if (!res) {
    - const char * (*get)(struct dentry *, struct inode *,
    - struct delayed_call *);
    - get = inode->i_op->get_link;
    - if (nd->flags & LOOKUP_RCU) {
    - res = get(NULL, inode, &last->done);
    - if (res == ERR_PTR(-ECHILD)) {
    - if (unlikely(unlazy_walk(nd)))
    - return ERR_PTR(-ECHILD);
    - res = get(dentry, inode, &last->done);
    - }
    - } else {
    - res = get(dentry, inode, &last->done);
    - }
    - if (!res)
    - goto all_done;
    - if (IS_ERR(res))
    - return res;
    - }
    - if (*res == '/') {
    - error = nd_jump_root(nd);
    - if (unlikely(error))
    - return ERR_PTR(error);
    - while (unlikely(*++res == '/'))
    - ;
    - }
    - if (*res)
    - return res;
    -all_done: // pure jump
    - put_link(nd);
    - return NULL;
    -}
    -
    /*
    * follow_up - Find the mountpoint of path's vfsmount
    *
    @@ -1796,8 +1726,10 @@ static inline int handle_dots(struct nameidata *nd, int type)
    static const char *pick_link(struct nameidata *nd, struct path *link,
    struct inode *inode, unsigned seq)
    {
    - int error;
    struct saved *last;
    + const char *res;
    + int error;
    +
    if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) {
    path_to_nameidata(link, nd);
    return ERR_PTR(-ELOOP);
    @@ -1828,9 +1760,64 @@ static const char *pick_link(struct nameidata *nd, struct path *link,
    last = nd->stack + nd->depth++;
    last->link = *link;
    clear_delayed_call(&last->done);
    - nd->link_inode = inode;
    last->seq = seq;
    - return get_link(nd);
    +
    + if (!(nd->flags & LOOKUP_PARENT)) {
    + error = may_follow_link(nd, inode);
    + if (unlikely(error))
    + return ERR_PTR(error);
    + }
    +
    + if (unlikely(nd->flags & LOOKUP_NO_SYMLINKS))
    + return ERR_PTR(-ELOOP);
    +
    + if (!(nd->flags & LOOKUP_RCU)) {
    + touch_atime(&last->link);
    + cond_resched();
    + } else if (atime_needs_update(&last->link, inode)) {
    + if (unlikely(unlazy_walk(nd)))
    + return ERR_PTR(-ECHILD);
    + touch_atime(&last->link);
    + }
    +
    + error = security_inode_follow_link(link->dentry, inode,
    + nd->flags & LOOKUP_RCU);
    + if (unlikely(error))
    + return ERR_PTR(error);
    +
    + nd->last_type = LAST_BIND;
    + res = READ_ONCE(inode->i_link);
    + if (!res) {
    + const char * (*get)(struct dentry *, struct inode *,
    + struct delayed_call *);
    + get = inode->i_op->get_link;
    + if (nd->flags & LOOKUP_RCU) {
    + res = get(NULL, inode, &last->done);
    + if (res == ERR_PTR(-ECHILD)) {
    + if (unlikely(unlazy_walk(nd)))
    + return ERR_PTR(-ECHILD);
    + res = get(link->dentry, inode, &last->done);
    + }
    + } else {
    + res = get(link->dentry, inode, &last->done);
    + }
    + if (!res)
    + goto all_done;
    + if (IS_ERR(res))
    + return res;
    + }
    + if (*res == '/') {
    + error = nd_jump_root(nd);
    + if (unlikely(error))
    + return ERR_PTR(error);
    + while (unlikely(*++res == '/'))
    + ;
    + }
    + if (*res)
    + return res;
    +all_done: // pure jump
    + put_link(nd);
    + return NULL;
    }

    enum {WALK_FOLLOW = 1, WALK_MORE = 2, WALK_NOFOLLOW = 4};
    --
    2.11.0
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