ext4: fix deadlock between inline_data and ext4_expand_extra_isize_ea()
The xattr_sem deadlock problems fixed in commit 2e81a4eeedca: "ext4:
avoid deadlock when expanding inode size" didn't include the use of
xattr_sem in fs/ext4/inline.c. With the addition of project quota
which added a new extra inode field, this exposed deadlocks in the
inline_data code similar to the ones fixed by 2e81a4eeedca.
The deadlock can be reproduced via:
dmesg -n 7
mke2fs -t ext4 -O inline_data -Fq -I 256 /dev/vdc 32768
mount -t ext4 -o debug_want_extra_isize=24 /dev/vdc /vdc
mkdir /vdc/a
umount /vdc
mount -t ext4 /dev/vdc /vdc
echo foo > /vdc/a/foo
and looks like this:
[ 11.158815]
[ 11.160276] =============================================
[ 11.161960] [ INFO: possible recursive locking detected ]
[ 11.161960] 4.10.0-rc3-00015-g011b30a8a3cf #160 Tainted: G W
[ 11.161960] ---------------------------------------------
[ 11.161960] bash/2519 is trying to acquire lock:
[ 11.161960] (&ei->xattr_sem){++++..}, at: [<c1225a4b>] ext4_expand_extra_isize_ea+0x3d/0x4cd
[ 11.161960]
[ 11.161960] but task is already holding lock:
[ 11.161960] (&ei->xattr_sem){++++..}, at: [<c1227941>] ext4_try_add_inline_entry+0x3a/0x152
[ 11.161960]
[ 11.161960] other info that might help us debug this:
[ 11.161960] Possible unsafe locking scenario:
[ 11.161960]
[ 11.161960] CPU0
[ 11.161960] ----
[ 11.161960] lock(&ei->xattr_sem);
[ 11.161960] lock(&ei->xattr_sem);
[ 11.161960]
[ 11.161960] *** DEADLOCK ***
[ 11.161960]
[ 11.161960] May be due to missing lock nesting notation
[ 11.161960]
[ 11.161960] 4 locks held by bash/2519:
[ 11.161960] #0: (sb_writers#3){.+.+.+}, at: [<c11a2414>] mnt_want_write+0x1e/0x3e
[ 11.161960] #1: (&type->i_mutex_dir_key){++++++}, at: [<c119508b>] path_openat+0x338/0x67a
[ 11.161960] #2: (jbd2_handle){++++..}, at: [<c123314a>] start_this_handle+0x582/0x622
[ 11.161960] #3: (&ei->xattr_sem){++++..}, at: [<c1227941>] ext4_try_add_inline_entry+0x3a/0x152
[ 11.161960]
[ 11.161960] stack backtrace:
[ 11.161960] CPU: 0 PID: 2519 Comm: bash Tainted: G W 4.10.0-rc3-00015-g011b30a8a3cf #160
[ 11.161960] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.1-1 04/01/2014
[ 11.161960] Call Trace:
[ 11.161960] dump_stack+0x72/0xa3
[ 11.161960] __lock_acquire+0xb7c/0xcb9
[ 11.161960] ? kvm_clock_read+0x1f/0x29
[ 11.161960] ? __lock_is_held+0x36/0x66
[ 11.161960] ? __lock_is_held+0x36/0x66
[ 11.161960] lock_acquire+0x106/0x18a
[ 11.161960] ? ext4_expand_extra_isize_ea+0x3d/0x4cd
[ 11.161960] down_write+0x39/0x72
[ 11.161960] ? ext4_expand_extra_isize_ea+0x3d/0x4cd
[ 11.161960] ext4_expand_extra_isize_ea+0x3d/0x4cd
[ 11.161960] ? _raw_read_unlock+0x22/0x2c
[ 11.161960] ? jbd2_journal_extend+0x1e2/0x262
[ 11.161960] ? __ext4_journal_get_write_access+0x3d/0x60
[ 11.161960] ext4_mark_inode_dirty+0x17d/0x26d
[ 11.161960] ? ext4_add_dirent_to_inline.isra.12+0xa5/0xb2
[ 11.161960] ext4_add_dirent_to_inline.isra.12+0xa5/0xb2
[ 11.161960] ext4_try_add_inline_entry+0x69/0x152
[ 11.161960] ext4_add_entry+0xa3/0x848
[ 11.161960] ? __brelse+0x14/0x2f
[ 11.161960] ? _raw_spin_unlock_irqrestore+0x44/0x4f
[ 11.161960] ext4_add_nondir+0x17/0x5b
[ 11.161960] ext4_create+0xcf/0x133
[ 11.161960] ? ext4_mknod+0x12f/0x12f
[ 11.161960] lookup_open+0x39e/0x3fb
[ 11.161960] ? __wake_up+0x1a/0x40
[ 11.161960] ? lock_acquire+0x11e/0x18a
[ 11.161960] path_openat+0x35c/0x67a
[ 11.161960] ? sched_clock_cpu+0xd7/0xf2
[ 11.161960] do_filp_open+0x36/0x7c
[ 11.161960] ? _raw_spin_unlock+0x22/0x2c
[ 11.161960] ? __alloc_fd+0x169/0x173
[ 11.161960] do_sys_open+0x59/0xcc
[ 11.161960] SyS_open+0x1d/0x1f
[ 11.161960] do_int80_syscall_32+0x4f/0x61
[ 11.161960] entry_INT80_32+0x2f/0x2f
[ 11.161960] EIP: 0xb76ad469
[ 11.161960] EFLAGS: 00000286 CPU: 0
[ 11.161960] EAX: ffffffda EBX: 08168ac8 ECX: 00008241 EDX: 000001b6
[ 11.161960] ESI: b75e46bc EDI: b7755000 EBP: bfbdb108 ESP: bfbdafc0
[ 11.161960] DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 007b
Cc: stable@vger.kernel.org # 3.10 (requires 2e81a4eeedca as a prereq)
Reported-by: George Spelvin <linux@sciencehorizons.net>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index 5a94fa52..c40bd55b6 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -1188,16 +1188,14 @@ ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
struct ext4_xattr_block_find bs = {
.s = { .not_found = -ENODATA, },
};
- unsigned long no_expand;
+ int no_expand;
int error;
if (!name)
return -EINVAL;
if (strlen(name) > 255)
return -ERANGE;
- down_write(&EXT4_I(inode)->xattr_sem);
- no_expand = ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND);
- ext4_set_inode_state(inode, EXT4_STATE_NO_EXPAND);
+ ext4_write_lock_xattr(inode, &no_expand);
error = ext4_reserve_inode_write(handle, inode, &is.iloc);
if (error)
@@ -1264,7 +1262,7 @@ ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
ext4_xattr_update_super_block(handle, inode->i_sb);
inode->i_ctime = current_time(inode);
if (!value)
- ext4_clear_inode_state(inode, EXT4_STATE_NO_EXPAND);
+ no_expand = 0;
error = ext4_mark_iloc_dirty(handle, inode, &is.iloc);
/*
* The bh is consumed by ext4_mark_iloc_dirty, even with
@@ -1278,9 +1276,7 @@ ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
cleanup:
brelse(is.iloc.bh);
brelse(bs.bh);
- if (no_expand == 0)
- ext4_clear_inode_state(inode, EXT4_STATE_NO_EXPAND);
- up_write(&EXT4_I(inode)->xattr_sem);
+ ext4_write_unlock_xattr(inode, &no_expand);
return error;
}
@@ -1497,12 +1493,11 @@ int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize,
int error = 0, tried_min_extra_isize = 0;
int s_min_extra_isize = le16_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_min_extra_isize);
int isize_diff; /* How much do we need to grow i_extra_isize */
+ int no_expand;
- down_write(&EXT4_I(inode)->xattr_sem);
- /*
- * Set EXT4_STATE_NO_EXPAND to avoid recursion when marking inode dirty
- */
- ext4_set_inode_state(inode, EXT4_STATE_NO_EXPAND);
+ if (ext4_write_trylock_xattr(inode, &no_expand) == 0)
+ return 0;
+
retry:
isize_diff = new_extra_isize - EXT4_I(inode)->i_extra_isize;
if (EXT4_I(inode)->i_extra_isize >= new_extra_isize)
@@ -1584,17 +1579,16 @@ int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize,
EXT4_I(inode)->i_extra_isize = new_extra_isize;
brelse(bh);
out:
- ext4_clear_inode_state(inode, EXT4_STATE_NO_EXPAND);
- up_write(&EXT4_I(inode)->xattr_sem);
+ ext4_write_unlock_xattr(inode, &no_expand);
return 0;
cleanup:
brelse(bh);
/*
- * We deliberately leave EXT4_STATE_NO_EXPAND set here since inode
- * size expansion failed.
+ * Inode size expansion failed; don't try again
*/
- up_write(&EXT4_I(inode)->xattr_sem);
+ no_expand = 1;
+ ext4_write_unlock_xattr(inode, &no_expand);
return error;
}
