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dcache: d_splice_alias should ignore DCACHE_DISCONNECTED

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Any IS_ROOT() alias should be safe to use; there's nothing special about
DCACHE_DISCONNECTED dentries.

Note that this is in fact useful for filesystems such as btrfs which can
legimately encounter a directory with a preexisting IS_ROOT alias on a
lookup that crosses into a subvolume.  (Those aliases are currently
marked DCACHE_DISCONNECTED--but not really for any good reason, and
we'll change that soon.)

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
J. Bruce Fields 2014-02-17 18:03:57 -05:00 committed by Al Viro
parent 908790fa3b
commit da093a9b76
1 changed files with 4 additions and 4 deletions
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8
fs/dcache.c
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@ -2649,9 +2649,9 @@ static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon)
* @inode: the inode which may have a disconnected dentry
* @dentry: a negative dentry which we want to point to the inode.
*
* If inode is a directory and has a 'disconnected' dentry (i.e. IS_ROOT and
* DCACHE_DISCONNECTED), then d_move that in place of the given dentry
* and return it, else simply d_add the inode to the dentry and return NULL.
* If inode is a directory and has an IS_ROOT alias, then d_move that in
* place of the given dentry and return it, else simply d_add the inode
* to the dentry and return NULL.
*
* If a non-IS_ROOT directory is found, the filesystem is corrupt, and
* we should error out: directories can't have multiple aliases.
@ -2678,7 +2678,7 @@ struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
spin_lock(&inode->i_lock);
new = __d_find_any_alias(inode);
if (new) {
if (!IS_ROOT(new) || !(new->d_flags & DCACHE_DISCONNECTED)) {
if (!IS_ROOT(new)) {
spin_unlock(&inode->i_lock);
dput(new);
return ERR_PTR(-EIO);