It turns out that not all directory inodes with dentries on the
i_dentry list are unusable here. We only consider them unusable if they
are still hashed or if they have a root dentry attached.
Full disclosure -- this check is inherently racy. There's nothing that
stops someone from slapping a new dentry onto this inode just after
this check, or hashing an existing one that's already attached. So,
this is really a "best effort" thing to work around misbehaving servers.
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
fs/cifs/inode.c | 43 +++++++++++++++++++++++++++++++------------
1 files changed, 31 insertions(+), 12 deletions(-)
diff --git a/fs/cifs/inode.c b/fs/cifs/inode.c
index 35e2466..1bfb8ec 100644
--- a/fs/cifs/inode.c
+++ b/fs/cifs/inode.c
@@ -736,15 +736,9 @@ cifs_find_inode(struct inode *inode, void *opaque)
if ((inode->i_mode & S_IFMT) != (fattr->cf_mode & S_IFMT))
return 0;
- /*
- * uh oh -- it's a directory. We can't use it since hardlinked dirs are
- * verboten. Disable serverino and return it as if it were found, the
- * caller can discard it, generate a uniqueid and retry the find
- */
- if (S_ISDIR(inode->i_mode) && !list_empty(&inode->i_dentry)) {
+ /* if it's not a directory or has no dentries, then flag it */
+ if (S_ISDIR(inode->i_mode) && !list_empty(&inode->i_dentry))
fattr->cf_flags |= CIFS_FATTR_INO_COLLISION;
- cifs_autodisable_serverino(CIFS_SB(inode->i_sb));
- }
return 1;
}
@@ -759,6 +753,27 @@ cifs_init_inode(struct inode *inode, void *opaque)
return 0;
}
+/*
+ * walk dentry list for an inode and report whether it has aliases that
+ * are hashed. We use this to determine if a directory inode can actually
+ * be used.
+ */
+static bool
+inode_has_hashed_dentries(struct inode *inode)
+{
+ struct dentry *dentry;
+
+ spin_lock(&dcache_lock);
+ list_for_each_entry(dentry, &inode->i_dentry, d_alias) {
+ if (!d_unhashed(dentry) || IS_ROOT(dentry)) {
+ spin_unlock(&dcache_lock);
+ return true;
+ }
+ }
+ spin_unlock(&dcache_lock);
+ return false;
+}
+
/* Given fattrs, get a corresponding inode */
struct inode *
cifs_iget(struct super_block *sb, struct cifs_fattr *fattr)
@@ -774,12 +789,16 @@ retry_iget5_locked:
inode = iget5_locked(sb, hash, cifs_find_inode, cifs_init_inode, fattr);
if (inode) {
- /* was there a problematic inode number collision? */
+ /* was there a potentially problematic inode collision? */
if (fattr->cf_flags & CIFS_FATTR_INO_COLLISION) {
- iput(inode);
- fattr->cf_uniqueid = iunique(sb, ROOT_I);
fattr->cf_flags &= ~CIFS_FATTR_INO_COLLISION;
- goto retry_iget5_locked;
+
+ if (inode_has_hashed_dentries(inode)) {
+ cifs_autodisable_serverino(CIFS_SB(sb));
+ iput(inode);
+ fattr->cf_uniqueid = iunique(sb, ROOT_I);
+ goto retry_iget5_locked;
+ }
}
cifs_fattr_to_inode(inode, fattr);
--
1.6.6.1
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