[3.8.y.z extended stable] Patch "Btrfs: fix inode caching vs tree log" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    Btrfs: fix inode caching vs tree log

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.24.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 90a397de3194edb8b8ddafbc39b6762e45a8e187 Mon Sep 17 00:00:00 2001
From: Miao Xie <miaox at cn.fujitsu.com>
Date: Wed, 23 Apr 2014 19:33:36 +0800
Subject: Btrfs: fix inode caching vs tree log

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 at cn.fujitsu.com>
Signed-off-by: Wang Shilong <wangsl.fnst at cn.fujitsu.com>
Signed-off-by: Chris Mason <clm at fb.com>
[ kamal: backport to 3.8-stable: context ]
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 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