This is a note to let you know that I've just added the patch titled
dentry_kill(): don't try to remove from shrink list
to the 3.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
dentry_kill-don-t-try-to-remove-from-shrink-list.patch
and it can be found in the queue-3.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 41edf278fc2f042f4e22a12ed87d19c5201210e1 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Thu, 1 May 2014 10:30:00 -0400
Subject: dentry_kill(): don't try to remove from shrink list
From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
commit 41edf278fc2f042f4e22a12ed87d19c5201210e1 upstream.
If the victim in on the shrink list, don't remove it from there.
If shrink_dentry_list() manages to remove it from the list before
we are done - fine, we'll just free it as usual. If not - mark
it with new flag (DCACHE_MAY_FREE) and leave it there.
Eventually, shrink_dentry_list() will get to it, remove the sucker
from shrink list and call dentry_kill(dentry, 0). Which is where
we'll deal with freeing.
Since now dentry_kill(dentry, 0) may happen after or during
dentry_kill(dentry, 1), we need to recognize that (by seeing
DCACHE_DENTRY_KILLED already set), unlock everything
and either free the sucker (in case DCACHE_MAY_FREE has been
set) or leave it for ongoing dentry_kill(dentry, 1) to deal with.
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: "Nicholas A. Bellinger" <nab@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/dcache.c | 27 +++++++++++++++++++--------
include/linux/dcache.h | 2 ++
2 files changed, 21 insertions(+), 8 deletions(-)
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -466,7 +466,14 @@ dentry_kill(struct dentry *dentry, int u
__releases(dentry->d_lock)
{
struct inode *inode;
- struct dentry *parent;
+ struct dentry *parent = NULL;
+ bool can_free = true;
+
+ if (unlikely(dentry->d_flags & DCACHE_DENTRY_KILLED)) {
+ can_free = dentry->d_flags & DCACHE_MAY_FREE;
+ spin_unlock(&dentry->d_lock);
+ goto out;
+ }
inode = dentry->d_inode;
if (inode && !spin_trylock(&inode->i_lock)) {
@@ -477,9 +484,7 @@ relock:
}
return dentry; /* try again with same dentry */
}
- if (IS_ROOT(dentry))
- parent = NULL;
- else
+ if (!IS_ROOT(dentry))
parent = dentry->d_parent;
if (parent && !spin_trylock(&parent->d_lock)) {
if (inode)
@@ -502,8 +507,6 @@ relock:
if (dentry->d_flags & DCACHE_LRU_LIST) {
if (!(dentry->d_flags & DCACHE_SHRINK_LIST))
d_lru_del(dentry);
- else
- d_shrink_del(dentry);
}
/* if it was on the hash then remove it */
__d_drop(dentry);
@@ -525,7 +528,15 @@ relock:
if (dentry->d_op && dentry->d_op->d_release)
dentry->d_op->d_release(dentry);
- dentry_free(dentry);
+ spin_lock(&dentry->d_lock);
+ if (dentry->d_flags & DCACHE_SHRINK_LIST) {
+ dentry->d_flags |= DCACHE_MAY_FREE;
+ can_free = false;
+ }
+ spin_unlock(&dentry->d_lock);
+out:
+ if (likely(can_free))
+ dentry_free(dentry);
return parent;
}
@@ -830,7 +841,7 @@ static void shrink_dentry_list(struct li
* We found an inuse dentry which was not removed from
* the LRU because of laziness during lookup. Do not free it.
*/
- if (dentry->d_lockref.count) {
+ if ((int)dentry->d_lockref.count > 0) {
spin_unlock(&dentry->d_lock);
continue;
}
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -221,6 +221,8 @@ struct dentry_operations {
#define DCACHE_SYMLINK_TYPE 0x00300000 /* Symlink */
#define DCACHE_FILE_TYPE 0x00400000 /* Other file type */
+#define DCACHE_MAY_FREE 0x00800000
+
extern seqlock_t rename_lock;
static inline int dname_external(const struct dentry *dentry)
Patches currently in stable-queue which might be from viro@xxxxxxxxxxxxxxxxxx are
queue-3.14/new-helper-dentry_free.patch
queue-3.14/don-t-remove-from-shrink-list-in-select_collect.patch
queue-3.14/fold-try_prune_one_dentry.patch
queue-3.14/more-graceful-recovery-in-umount_collect.patch
queue-3.14/expand-the-call-of-dentry_lru_del-in-dentry_kill.patch
queue-3.14/dcache-don-t-need-rcu-in-shrink_dentry_list.patch
queue-3.14/path_openat-fix-double-fput.patch
queue-3.14/fold-d_kill-and-d_free.patch
queue-3.14/ipc-modify-message-queue-accounting-to-not-take-kernel-data-structures-into-account.patch
queue-3.14/dentry_kill-don-t-try-to-remove-from-shrink-list.patch
queue-3.14/sg_start_req-make-sure-that-there-s-not-too-many-elements-in-iovec.patch
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