This is a note to let you know that I've just added the patch titled
ext4: Resolve the hang of direct i/o read in handling EXT4_IO_END_UNWRITTEN.
to the 3.0-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-resolve-the-hang-of-direct-i-o-read-in-handling-ext4_io_end_unwritten.patch
and it can be found in the queue-3.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 32c80b32c053dc52712dedac5e4d0aa7c93fc353 Mon Sep 17 00:00:00 2001
From: Tao Ma <[email protected]>
Date: Sat, 13 Aug 2011 12:30:59 -0400
Subject: ext4: Resolve the hang of direct i/o read in handling
EXT4_IO_END_UNWRITTEN.
From: Tao Ma <[email protected]>
commit 32c80b32c053dc52712dedac5e4d0aa7c93fc353 upstream.
EXT4_IO_END_UNWRITTEN flag set and the increase of i_aiodio_unwritten
should be done simultaneously since ext4_end_io_nolock always clear
the flag and decrease the counter in the same time.
We don't increase i_aiodio_unwritten when setting
EXT4_IO_END_UNWRITTEN so it will go nagative and causes some process
to wait forever.
Part of the patch came from Eric in his e-mail, but it doesn't fix the
problem met by Michael actually.
http://marc.info/?l=linux-ext4&m=131316851417460&w=2
Reported-and-Tested-by: Michael Tokarev<[email protected]>
Signed-off-by: Eric Sandeen <[email protected]>
Signed-off-by: Tao Ma <[email protected]>
Signed-off-by: "Theodore Ts'o" <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
fs/ext4/inode.c | 9 ++++++++-
fs/ext4/page-io.c | 6 ++++--
2 files changed, 12 insertions(+), 3 deletions(-)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3645,8 +3645,15 @@ static void ext4_end_io_buffer_write(str
goto out;
}
- io_end->flag = EXT4_IO_END_UNWRITTEN;
+ /*
+ * It may be over-defensive here to check EXT4_IO_END_UNWRITTEN now,
+ * but being more careful is always safe for the future change.
+ */
inode = io_end->inode;
+ if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) {
+ io_end->flag |= EXT4_IO_END_UNWRITTEN;
+ atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten);
+ }
/* Add the io_end to per-inode completed io list*/
spin_lock_irqsave(&EXT4_I(inode)->i_completed_io_lock, flags);
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -338,8 +338,10 @@ submit_and_retry:
if ((io_end->num_io_pages >= MAX_IO_PAGES) &&
(io_end->pages[io_end->num_io_pages-1] != io_page))
goto submit_and_retry;
- if (buffer_uninit(bh))
- io->io_end->flag |= EXT4_IO_END_UNWRITTEN;
+ if (buffer_uninit(bh) && !(io_end->flag & EXT4_IO_END_UNWRITTEN)) {
+ io_end->flag |= EXT4_IO_END_UNWRITTEN;
+ atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten);
+ }
io->io_end->size += bh->b_size;
io->io_next_block++;
ret = bio_add_page(io->io_bio, bh->b_page, bh->b_size, bh_offset(bh));
Patches currently in stable-queue which might be from [email protected] are
queue-3.0/ext4-resolve-the-hang-of-direct-i-o-read-in-handling-ext4_io_end_unwritten.patch
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