This is a note to let you know that I've just added the patch titled
ext4: fix deadlock when writing in ENOSPC conditions
to the 3.12-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ext4-fix-deadlock-when-writing-in-enospc-conditions.patch
and it can be found in the queue-3.12 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 34cf865d54813aab3497838132fb1bbd293f4054 Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@xxxxxxx>
Date: Wed, 18 Dec 2013 00:44:44 -0500
Subject: ext4: fix deadlock when writing in ENOSPC conditions
From: Jan Kara <jack@xxxxxxx>
commit 34cf865d54813aab3497838132fb1bbd293f4054 upstream.
Akira-san has been reporting rare deadlocks of his machine when running
xfstests test 269 on ext4 filesystem. The problem turned out to be in
ext4_da_reserve_metadata() and ext4_da_reserve_space() which called
ext4_should_retry_alloc() while holding i_data_sem. Since
ext4_should_retry_alloc() can force a transaction commit, this is a
lock ordering violation and leads to deadlocks.
Fix the problem by just removing the retry loops. These functions should
just report ENOSPC to the caller (e.g. ext4_da_write_begin()) and that
function must take care of retrying after dropping all necessary locks.
Reported-and-tested-by: Akira Fujita <a-fujita@xxxxxxxxxxxxx>
Reviewed-by: Zheng Liu <wenqing.lz@xxxxxxxxxx>
Signed-off-by: Jan Kara <jack@xxxxxxx>
Signed-off-by: "Theodore Ts'o" <tytso@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/ext4/inode.c | 12 ------------
1 file changed, 12 deletions(-)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1206,7 +1206,6 @@ static int ext4_journalled_write_end(str
*/
static int ext4_da_reserve_metadata(struct inode *inode, ext4_lblk_t lblock)
{
- int retries = 0;
struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
struct ext4_inode_info *ei = EXT4_I(inode);
unsigned int md_needed;
@@ -1218,7 +1217,6 @@ static int ext4_da_reserve_metadata(stru
* in order to allocate nrblocks
* worse case is one extent per block
*/
-repeat:
spin_lock(&ei->i_block_reservation_lock);
/*
* ext4_calc_metadata_amount() has side effects, which we have
@@ -1238,10 +1236,6 @@ repeat:
ei->i_da_metadata_calc_len = save_len;
ei->i_da_metadata_calc_last_lblock = save_last_lblock;
spin_unlock(&ei->i_block_reservation_lock);
- if (ext4_should_retry_alloc(inode->i_sb, &retries)) {
- cond_resched();
- goto repeat;
- }
return -ENOSPC;
}
ei->i_reserved_meta_blocks += md_needed;
@@ -1255,7 +1249,6 @@ repeat:
*/
static int ext4_da_reserve_space(struct inode *inode, ext4_lblk_t lblock)
{
- int retries = 0;
struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
struct ext4_inode_info *ei = EXT4_I(inode);
unsigned int md_needed;
@@ -1277,7 +1270,6 @@ static int ext4_da_reserve_space(struct
* in order to allocate nrblocks
* worse case is one extent per block
*/
-repeat:
spin_lock(&ei->i_block_reservation_lock);
/*
* ext4_calc_metadata_amount() has side effects, which we have
@@ -1297,10 +1289,6 @@ repeat:
ei->i_da_metadata_calc_len = save_len;
ei->i_da_metadata_calc_last_lblock = save_last_lblock;
spin_unlock(&ei->i_block_reservation_lock);
- if (ext4_should_retry_alloc(inode->i_sb, &retries)) {
- cond_resched();
- goto repeat;
- }
dquot_release_reservation_block(inode, EXT4_C2B(sbi, 1));
return -ENOSPC;
}
Patches currently in stable-queue which might be from jack@xxxxxxx are
queue-3.12/ext4-fix-deadlock-when-writing-in-enospc-conditions.patch
queue-3.12/ext4-call-ext4_error_inode-if-jbd2_journal_dirty_metadata-fails.patch
queue-3.12/ext4-do-not-reserve-clusters-when-fs-doesn-t-support-extents.patch
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