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namei: explicitly pass seq number to unlazy_walk() when dentry != NULL

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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2015-05-05 09:26:05 -04:00
parent 3595e2346c
commit 6e9918b7b3
1 changed files with 8 additions and 7 deletions
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15
fs/namei.c
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@ -567,13 +567,14 @@ static inline int nd_alloc_stack(struct nameidata *nd)
* unlazy_walk - try to switch to ref-walk mode.
* @nd: nameidata pathwalk data
* @dentry: child of nd->path.dentry or NULL
* @seq: seq number to check dentry against
* Returns: 0 on success, -ECHILD on failure
*
* unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry
* for ref-walk mode. @dentry must be a path found by a do_lookup call on
* @nd or NULL. Must be called from rcu-walk context.
*/
static int unlazy_walk(struct nameidata *nd, struct dentry *dentry)
static int unlazy_walk(struct nameidata *nd, struct dentry *dentry, unsigned seq)
{
struct fs_struct *fs = current->fs;
struct dentry *parent = nd->path.dentry;
@ -615,7 +616,7 @@ static int unlazy_walk(struct nameidata *nd, struct dentry *dentry)
} else {
if (!lockref_get_not_dead(&dentry->d_lockref))
goto out;
if (read_seqcount_retry(&dentry->d_seq, nd->seq))
if (read_seqcount_retry(&dentry->d_seq, seq))
goto drop_dentry;
}
@ -671,7 +672,7 @@ static int complete_walk(struct nameidata *nd)
if (nd->flags & LOOKUP_RCU) {
if (!(nd->flags & LOOKUP_ROOT))
nd->root.mnt = NULL;
if (unlikely(unlazy_walk(nd, NULL)))
if (unlikely(unlazy_walk(nd, NULL, 0)))
return -ECHILD;
}
@ -1451,7 +1452,7 @@ static int lookup_fast(struct nameidata *nd,
if (likely(__follow_mount_rcu(nd, path, inode)))
return 0;
unlazy:
if (unlazy_walk(nd, dentry))
if (unlazy_walk(nd, dentry, nd->seq))
return -ECHILD;
} else {
dentry = __d_lookup(parent, &nd->last);
@ -1511,7 +1512,7 @@ static inline int may_lookup(struct nameidata *nd)
int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK);
if (err != -ECHILD)
return err;
if (unlazy_walk(nd, NULL))
if (unlazy_walk(nd, NULL, 0))
return -ECHILD;
}
return inode_permission(nd->inode, MAY_EXEC);
@ -1552,7 +1553,7 @@ static int pick_link(struct nameidata *nd, struct path *link)
}
if (nd->flags & LOOKUP_RCU) {
if (unlikely(nd->path.mnt != link->mnt ||
unlazy_walk(nd, link->dentry))) {
unlazy_walk(nd, link->dentry, nd->seq))) {
return -ECHILD;
}
}
@ -2297,7 +2298,7 @@ mountpoint_last(struct nameidata *nd, struct path *path)
/* If we're in rcuwalk, drop out of it to handle last component */
if (nd->flags & LOOKUP_RCU) {
if (unlazy_walk(nd, NULL))
if (unlazy_walk(nd, NULL, 0))
return -ECHILD;
}