[PATCH 3.8 038/121] Btrfs: fix inode caching vs tree log

From: Kamal Mostafa
Date: Tue Jun 17 2014 - 12:53:55 EST


3.8.13.24 -stable review patch. If anyone has any objections, please let me know.

------------------

From: Miao Xie <miaox@xxxxxxxxxxxxxx>

commit 1c70d8fb4dfa95bee491816b2a6767b5ca1080e7 upstream.

Currently, with inode cache enabled, we will reuse its inode id immediately
after unlinking file, we may hit something like following:

|->iput inode
|->return inode id into inode cache
|->create dir,fsync
|->power off

An easy way to reproduce this problem is:

mkfs.btrfs -f /dev/sdb
mount /dev/sdb /mnt -o inode_cache,commit=100
dd if=/dev/zero of=/mnt/data bs=1M count=10 oflag=sync
inode_id=`ls -i /mnt/data | awk '{print $1}'`
rm -f /mnt/data

i=1
while [ 1 ]
do
mkdir /mnt/dir_$i
test1=`stat /mnt/dir_$i | grep Inode: | awk '{print $4}'`
if [ $test1 -eq $inode_id ]
then
dd if=/dev/zero of=/mnt/dir_$i/data bs=1M count=1 oflag=sync
echo b > /proc/sysrq-trigger
fi
sleep 1
i=$(($i+1))
done

mount /dev/sdb /mnt
umount /dev/sdb
btrfs check /dev/sdb

We fix this problem by adding unlinked inode's id into pinned tree,
and we can not reuse them until committing transaction.

Signed-off-by: Miao Xie <miaox@xxxxxxxxxxxxxx>
Signed-off-by: Wang Shilong <wangsl.fnst@xxxxxxxxxxxxxx>
Signed-off-by: Chris Mason <clm@xxxxxx>
[ kamal: backport to 3.8-stable: context ]
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
fs/btrfs/inode-map.c | 18 ++----------------
1 file changed, 2 insertions(+), 16 deletions(-)

diff --git a/fs/btrfs/inode-map.c b/fs/btrfs/inode-map.c
index d26f67a..9e2a340 100644
--- a/fs/btrfs/inode-map.c
+++ b/fs/btrfs/inode-map.c
@@ -207,24 +207,14 @@ again:

void btrfs_return_ino(struct btrfs_root *root, u64 objectid)
{
- struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
struct btrfs_free_space_ctl *pinned = root->free_ino_pinned;

if (!btrfs_test_opt(root, INODE_MAP_CACHE))
return;
-
again:
if (root->cached == BTRFS_CACHE_FINISHED) {
- __btrfs_add_free_space(ctl, objectid, 1);
+ __btrfs_add_free_space(pinned, objectid, 1);
} else {
- /*
- * If we are in the process of caching free ino chunks,
- * to avoid adding the same inode number to the free_ino
- * tree twice due to cross transaction, we'll leave it
- * in the pinned tree until a transaction is committed
- * or the caching work is done.
- */
-
mutex_lock(&root->fs_commit_mutex);
spin_lock(&root->cache_lock);
if (root->cached == BTRFS_CACHE_FINISHED) {
@@ -236,11 +226,7 @@ again:

start_caching(root);

- if (objectid <= root->cache_progress ||
- objectid > root->highest_objectid)
- __btrfs_add_free_space(ctl, objectid, 1);
- else
- __btrfs_add_free_space(pinned, objectid, 1);
+ __btrfs_add_free_space(pinned, objectid, 1);

mutex_unlock(&root->fs_commit_mutex);
}
--
1.9.1

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