Some times we call ->write_begin() with opened journal
but write_begin() may internally call ext4_should_retry_alloc()
in case of ENOSPC, which result in deadlock.
This patch introduce new AOP_FLAG which should be tested on retry
alloc path.
Signed-off-by: Dmitry Monakhov <[email protected]>
---
fs/ext4/ext4.h | 5 +++++
fs/ext4/inode.c | 6 ++++--
fs/ext4/move_extent.c | 2 +-
include/linux/fs.h | 1 +
4 files changed, 11 insertions(+), 3 deletions(-)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index af7b626..0efb224 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -792,6 +792,11 @@ struct ext4_inode_info {
#define EXT4_DFL_CHECKINTERVAL 0 /* Don't use interval check */
/*
+ * Address space flags.
+ */
+#define EXT4_AOP_FLAG_NORETRY AOP_FLAG_LAST /* Do not allow to fail in to
+ retry alloc loop */
+/*
* Behaviour when detecting errors
*/
#define EXT4_ERRORS_CONTINUE 1 /* Continue execution */
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index c818972..2d3fe4d 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1593,7 +1593,8 @@ retry:
}
}
- if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
+ if (!(flags & EXT4_AOP_FLAG_NORETRY) && ret == -ENOSPC &&
+ ext4_should_retry_alloc(inode->i_sb, &retries))
goto retry;
out:
return ret;
@@ -3089,7 +3090,8 @@ retry:
ext4_truncate_failed_write(inode);
}
- if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
+ if (!(flags & EXT4_AOP_FLAG_NORETRY) &&
+ ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
goto retry;
out:
return ret;
diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c
index 82c415b..f894382 100644
--- a/fs/ext4/move_extent.c
+++ b/fs/ext4/move_extent.c
@@ -796,7 +796,7 @@ move_extent_per_page(struct file *o_filp, struct inode *donor_inode,
ext4_lblk_t orig_blk_offset;
long long offs = orig_page_offset << PAGE_CACHE_SHIFT;
unsigned long blocksize = orig_inode->i_sb->s_blocksize;
- unsigned int w_flags = 0;
+ unsigned int w_flags = EXT4_AOP_FLAG_NORETRY;
unsigned int tmp_data_size, data_size, replaced_size;
void *fsdata;
int i, jblocks;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index b1bcb27..6f68707 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -504,6 +504,7 @@ enum positive_aop_returns {
#define AOP_FLAG_NOFS 0x0004 /* used by filesystem to direct
* helper code (eg buffer layer)
* to clear GFP_FS from alloc */
+#define AOP_FLAG_LAST 0x0008 /* First unused private flag */
/*
* oh the beauties of C type declarations.
--
1.6.3.3
On Wed, 03 Feb 2010 21:27:31 +0300, Dmitry Monakhov <[email protected]> wrote:
>
> Some times we call ->write_begin() with opened journal
> but write_begin() may internally call ext4_should_retry_alloc()
> in case of ENOSPC, which result in deadlock.
> This patch introduce new AOP_FLAG which should be tested on retry
> alloc path.
>
Can you explain this further. We do a journal_stop before
ext4_should_retry_alloc. So not sure about the deadlock.
-aneesh
"Aneesh Kumar K. V" <[email protected]> writes:
> On Wed, 03 Feb 2010 21:27:31 +0300, Dmitry Monakhov <[email protected]> wrote:
>>
>> Some times we call ->write_begin() with opened journal
>> but write_begin() may internally call ext4_should_retry_alloc()
>> in case of ENOSPC, which result in deadlock.
>> This patch introduce new AOP_FLAG which should be tested on retry
>> alloc path.
>>
>
> Can you explain this further. We do a journal_stop before
> ext4_should_retry_alloc. So not sure about the deadlock.
move_extent_per_page
ext4_journal_start -> current->journal_info != NULL
->write_begin
ext4_journal_start
ext4_journal_stop
ext4_should_retry_alloc : here current->journal_info != NULL
Sorry i've missed the fact that ext4_should_retry_alloc() check
for current->journal_info and skip running transaction in that case.
Seems what this check was added long time ago, but i miss it.
So this patch is useless.
>
> -aneesh