Dmitry Monakhov <dmonakhov@xxxxxxxxxx> writes:
> Theodore please review this patch ASAP, currently ext4+quota is
> fatally broken due to your patch. Christmas holidays when you
> submit your patch is not good time for good review, IMHO
> i was too lazy to review it carefully.
> Testcase is trivial it is enough just hit a quota barrier.
> dmon$ set-quota-limit /mnt id=dmon --bsoft=1000 --bsoft=1000
> dmon$ dd if=/dev/zefo of=/mnt/file
>
> kernel BUG at fs/jbd2/transaction.c:1027!
OOps, i'm sorry. seems that i've send wrong patch version
the only difference is follows:
- dqretry = (ret == -EDQUOT) || EXT4_I(inode)->i_reserved_meta_blocks;
+ dqretry = (ret == -EDQUOT) && EXT4_I(inode)->i_reserved_meta_blocks;
Correct version attached.
>From 3dd53f88470fdc4ec3f06da34cfc760fa8359be8 Mon Sep 17 00:00:00 2001
From: Dmitry Monakhov <dmonakhov@xxxxxxxxxx>
Date: Wed, 3 Feb 2010 22:03:17 +0300
Subject: [PATCH 2/2] ext4: fix delalloc retry loop logic -v2
Current delalloc write path is broken:
ext4_da_write_begin()
ext4_journal_start(inode, 1); -> current->journal != NULL
block_write_begin
ext4_da_get_block_prep()
ext4_da_reserve_space()
ext4_should_retry_alloc() -> deadlock
write_inode_now() -> BUG_ON due to lack of journal credits
Bug was partly introduced by following commit:
0637c6f4135f592f094207c7c21e7c0fc5557834
ext4: Patch up how we claim metadata blocks for quota purposes
In order to preserve retry logic and eliminate bugs we have to
move retry loop to ext4_da_write_begin()
Signed-off-by: Dmitry Monakhov <dmonakhov@xxxxxxxxxx>
---
fs/ext4/inode.c | 41 ++++++++++++++++++-----------------------
1 files changed, 18 insertions(+), 23 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 2d3fe4d..bd9e573 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1815,7 +1815,6 @@ static int ext4_journalled_write_end(struct file *file,
*/
static int ext4_da_reserve_space(struct inode *inode, sector_t lblock)
{
- int retries = 0;
struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
struct ext4_inode_info *ei = EXT4_I(inode);
unsigned long md_needed, md_reserved;
@@ -1825,7 +1824,6 @@ static int ext4_da_reserve_space(struct inode *inode, sector_t lblock)
* in order to allocate nrblocks
* worse case is one extent per block
*/
-repeat:
spin_lock(&ei->i_block_reservation_lock);
md_reserved = ei->i_reserved_meta_blocks;
md_needed = ext4_calc_metadata_amount(inode, lblock);
@@ -1836,27 +1834,11 @@ repeat:
* later. Real quota accounting is done at pages writeout
* time.
*/
- if (vfs_dq_reserve_block(inode, md_needed + 1)) {
- /*
- * We tend to badly over-estimate the amount of
- * metadata blocks which are needed, so if we have
- * reserved any metadata blocks, try to force out the
- * inode and see if we have any better luck.
- */
- if (md_reserved && retries++ <= 3)
- goto retry;
+ if (vfs_dq_reserve_block(inode, md_needed + 1))
return -EDQUOT;
- }
if (ext4_claim_free_blocks(sbi, md_needed + 1)) {
vfs_dq_release_reservation_block(inode, md_needed + 1);
- if (ext4_should_retry_alloc(inode->i_sb, &retries)) {
- retry:
- if (md_reserved)
- write_inode_now(inode, (retries == 3));
- yield();
- goto repeat;
- }
return -ENOSPC;
}
spin_lock(&ei->i_block_reservation_lock);
@@ -3033,7 +3015,7 @@ static int ext4_da_write_begin(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned flags,
struct page **pagep, void **fsdata)
{
- int ret, retries = 0;
+ int ret, dqretry, retries = 0;
struct page *page;
pgoff_t index;
unsigned from, to;
@@ -3090,9 +3072,22 @@ retry:
ext4_truncate_failed_write(inode);
}
- if (!(flags & EXT4_AOP_FLAG_NORETRY) &&
- ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
- goto retry;
+ dqretry = (ret == -EDQUOT) && EXT4_I(inode)->i_reserved_meta_blocks;
+ if ( !(flags & EXT4_AOP_FLAG_NORETRY) &&
+ (ret == -ENOSPC || dqretry) &&
+ ext4_should_retry_alloc(inode->i_sb, &retries)) {
+ if (dqretry) {
+ /*
+ * We tend to badly over-estimate the amount of
+ * metadata blocks which are needed, so if we have
+ * reserved any metadata blocks, try to force out the
+ * inode and see if we have any better luck.
+ */
+ write_inode_now(inode, (retries == 3));
+ }
+ yield();
+ goto retry;
+ }
out:
return ret;
}
--
1.6.3.3
