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authorJan Kara <jack@suse.cz>2011-05-30 13:29:20 +0200
committerGreg Kroah-Hartman <gregkh@suse.de>2011-08-08 10:23:13 -0700
commit98aea907860bce247af40351a297d56ef44d7f26 (patch)
tree051b79240668a03e6755fc9dac880988c5029da8
parentb259a3c0e4348587e06fbabd828fb878457c5dad (diff)
downloadlinux-linaro-stable-98aea907860bce247af40351a297d56ef44d7f26.tar.gz
ext3: Fix oops in ext3_try_to_allocate_with_rsv()
commit ad95c5e9bc8b5885f94dce720137cac8fa8da4c9 upstream. Block allocation is called from two places: ext3_get_blocks_handle() and ext3_xattr_block_set(). These two callers are not necessarily synchronized because xattr code holds only xattr_sem and i_mutex, and ext3_get_blocks_handle() may hold only truncate_mutex when called from writepage() path. Block reservation code does not expect two concurrent allocations to happen to the same inode and thus assertions can be triggered or reservation structure corruption can occur. Fix the problem by taking truncate_mutex in xattr code to serialize allocations. CC: Sage Weil <sage@newdream.net> Reported-by: Fyodor Ustinov <ufm@ufm.su> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--fs/ext3/xattr.c12
1 files changed, 10 insertions, 2 deletions
diff --git a/fs/ext3/xattr.c b/fs/ext3/xattr.c
index 387d92d00b97..d7add4ca2e53 100644
--- a/fs/ext3/xattr.c
+++ b/fs/ext3/xattr.c
@@ -800,8 +800,16 @@ inserted:
/* We need to allocate a new block */
ext3_fsblk_t goal = ext3_group_first_block_no(sb,
EXT3_I(inode)->i_block_group);
- ext3_fsblk_t block = ext3_new_block(handle, inode,
- goal, &error);
+ ext3_fsblk_t block;
+
+ /*
+ * Protect us agaist concurrent allocations to the
+ * same inode from ext3_..._writepage(). Reservation
+ * code does not expect racing allocations.
+ */
+ mutex_lock(&EXT3_I(inode)->truncate_mutex);
+ block = ext3_new_block(handle, inode, goal, &error);
+ mutex_unlock(&EXT3_I(inode)->truncate_mutex);
if (error)
goto cleanup;
ea_idebug(inode, "creating block %d", block);