[patch 089/104] ext4: fix xattr deadlock

Greg KH
2008-12-03T20:26:19Z

[-- Attachment #1: ext4-fix-xattr-deadlock.patch --]
[-- Type: text/plain, Size: 1581 bytes --]

2.6.27-stable review patch. If anyone has any objections, please let us know.

------------------
From: Kalpak Shah <kalpak.shah@sun.com>

(cherry picked from commit 4d20c685fa365766a8f13584b4c8178a15ab7103)

ext4_xattr_set_handle() eventually ends up calling
ext4_mark_inode_dirty() which tries to expand the inode by shifting
the EAs. This leads to the xattr_sem being downed again and leading
to a deadlock.

This patch makes sure that if ext4_xattr_set_handle() is in the
call-chain, ext4_mark_inode_dirty() will not expand the inode.

Signed-off-by: Kalpak Shah <kalpak.shah@sun.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
fs/ext4/xattr.c | 6 ++++++
1 file changed, 6 insertions(+)

--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -959,6 +959,7 @@ ext4_xattr_set_handle(handle_t *handle,
struct ext4_xattr_block_find bs = {
.s = { .not_found = -ENODATA, },
};
+ unsigned long no_expand;
int error;

if (!name)
@@ -966,6 +967,9 @@ ext4_xattr_set_handle(handle_t *handle,
if (strlen(name) > 255)
return -ERANGE;
down_write(&EXT4_I(inode)->xattr_sem);
+ no_expand = EXT4_I(inode)->i_state & EXT4_STATE_NO_EXPAND;
+ EXT4_I(inode)->i_state |= EXT4_STATE_NO_EXPAND;
+
error = ext4_get_inode_loc(inode, &is.iloc);
if (error)
goto cleanup;
@@ -1042,6 +1046,8 @@ ext4_xattr_set_handle(handle_t *handle,
cleanup:
brelse(is.iloc.bh);
brelse(bs.bh);
+ if (no_expand == 0)
+ EXT4_I(inode)->i_state &= ~EXT4_STATE_NO_EXPAND;
up_write(&EXT4_I(inode)->xattr_sem);
return error;
}