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authorMiklos Szeredi <mszeredi@suse.cz>2012-09-17 22:31:38 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-10-02 09:47:23 -0700
commit8b2b69f4e7a4cd7768323f84f17f09ab608e620d (patch)
tree3e1ed29fc5a8f92522019496e8d4086414f357fa
parentc168d49dbb4bc6cbd58b855166e5f98585479307 (diff)
vfs: dcache: use DCACHE_DENTRY_KILLED instead of DCACHE_DISCONNECTED in d_kill()
commit b161dfa6937ae46d50adce8a7c6b12233e96e7bd upstream. IBM reported a soft lockup after applying the fix for the rename_lock deadlock. Commit c83ce989cb5f ("VFS: Fix the nfs sillyrename regression in kernel 2.6.38") was found to be the culprit. The nfs sillyrename fix used DCACHE_DISCONNECTED to indicate that the dentry was killed. This flag can be set on non-killed dentries too, which results in infinite retries when trying to traverse the dentry tree. This patch introduces a separate flag: DCACHE_DENTRY_KILLED, which is only set in d_kill() and makes try_to_ascend() test only this flag. IBM reported successful test results with this patch. Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Cc: Trond Myklebust <Trond.Myklebust@netapp.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--fs/dcache.c4
-rw-r--r--include/linux/dcache.h2
2 files changed, 4 insertions, 2 deletions
diff --git a/fs/dcache.c b/fs/dcache.c
index 0b51cfc9291..bd8aaf66140 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -290,7 +290,7 @@ static struct dentry *d_kill(struct dentry *dentry, struct dentry *parent)
* Inform try_to_ascend() that we are no longer attached to the
* dentry tree
*/
- dentry->d_flags |= DCACHE_DISCONNECTED;
+ dentry->d_flags |= DCACHE_DENTRY_KILLED;
if (parent)
spin_unlock(&parent->d_lock);
dentry_iput(dentry);
@@ -1015,7 +1015,7 @@ static struct dentry *try_to_ascend(struct dentry *old, int locked, unsigned seq
* or deletion
*/
if (new != old->d_parent ||
- (old->d_flags & DCACHE_DISCONNECTED) ||
+ (old->d_flags & DCACHE_DENTRY_KILLED) ||
(!locked && read_seqretry(&rename_lock, seq))) {
spin_unlock(&new->d_lock);
new = NULL;
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index f13bb6dd156..7d6a6b867f2 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -220,6 +220,8 @@ struct dentry_operations {
#define DCACHE_MANAGED_DENTRY \
(DCACHE_MOUNTED|DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT)
+#define DCACHE_DENTRY_KILLED 0x100000
+
extern seqlock_t rename_lock;
static inline int dname_external(struct dentry *dentry)