This is a note to let you know that I've just added the patch titled
ext4: move unlocked dio protection from ext4_alloc_file_blocks()
to the 4.4-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-move-unlocked-dio-protection-from-ext4_alloc_file_blocks.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 17048e8a083fec7ad841d88ef0812707fbc7e39f Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@xxxxxxxx>
Date: Mon, 7 Dec 2015 14:29:17 -0500
Subject: ext4: move unlocked dio protection from ext4_alloc_file_blocks()
From: Jan Kara <jack@xxxxxxxx>
commit 17048e8a083fec7ad841d88ef0812707fbc7e39f upstream.
Currently ext4_alloc_file_blocks() was handling protection against
unlocked DIO. However we now need to sometimes call it under i_mmap_sem
and sometimes not and DIO protection ranks above it (although strictly
speaking this cannot currently create any deadlocks). Also
ext4_zero_range() was actually getting & releasing unlocked DIO
protection twice in some cases. Luckily it didn't introduce any real bug
but it was a land mine waiting to be stepped on. So move DIO protection
out from ext4_alloc_file_blocks() into the two callsites.
Signed-off-by: Jan Kara <jack@xxxxxxxx>
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/ext4/extents.c | 21 ++++++++++-----------
1 file changed, 10 insertions(+), 11 deletions(-)
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -4685,10 +4685,6 @@ static int ext4_alloc_file_blocks(struct
if (len <= EXT_UNWRITTEN_MAX_LEN)
flags |= EXT4_GET_BLOCKS_NO_NORMALIZE;
- /* Wait all existing dio workers, newcomers will block on i_mutex */
- ext4_inode_block_unlocked_dio(inode);
- inode_dio_wait(inode);
-
/*
* credits to insert 1 extent into extent tree
*/
@@ -4752,8 +4748,6 @@ retry:
goto retry;
}
- ext4_inode_resume_unlocked_dio(inode);
-
return ret > 0 ? ret2 : ret;
}
@@ -4827,6 +4821,10 @@ static long ext4_zero_range(struct file
if (mode & FALLOC_FL_KEEP_SIZE)
flags |= EXT4_GET_BLOCKS_KEEP_SIZE;
+ /* Wait all existing dio workers, newcomers will block on i_mutex */
+ ext4_inode_block_unlocked_dio(inode);
+ inode_dio_wait(inode);
+
/* Preallocate the range including the unaligned edges */
if (partial_begin || partial_end) {
ret = ext4_alloc_file_blocks(file,
@@ -4835,7 +4833,7 @@ static long ext4_zero_range(struct file
round_down(offset, 1 << blkbits)) >> blkbits,
new_size, flags, mode);
if (ret)
- goto out_mutex;
+ goto out_dio;
}
@@ -4844,10 +4842,6 @@ static long ext4_zero_range(struct file
flags |= (EXT4_GET_BLOCKS_CONVERT_UNWRITTEN |
EXT4_EX_NOCACHE);
- /* Wait all existing dio workers, newcomers will block on i_mutex */
- ext4_inode_block_unlocked_dio(inode);
- inode_dio_wait(inode);
-
/*
* Prevent page faults from reinstantiating pages we have
* released from page cache.
@@ -4992,8 +4986,13 @@ long ext4_fallocate(struct file *file, i
goto out;
}
+ /* Wait all existing dio workers, newcomers will block on i_mutex */
+ ext4_inode_block_unlocked_dio(inode);
+ inode_dio_wait(inode);
+
ret = ext4_alloc_file_blocks(file, lblk, max_blocks, new_size,
flags, mode);
+ ext4_inode_resume_unlocked_dio(inode);
if (ret)
goto out;
Patches currently in stable-queue which might be from jack@xxxxxxxx are
queue-4.4/ext4-fix-races-between-page-faults-and-hole-punching.patch
queue-4.4/ext4-move-unlocked-dio-protection-from-ext4_alloc_file_blocks.patch
queue-4.4/ext4-fix-races-between-buffered-io-and-collapse-insert-range.patch
queue-4.4/ext4-fix-races-of-writeback-with-punch-hole-and-zero-range.patch
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