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| author | Tao Ma <boyu.mt@taobao.com> | 2011-08-13 12:30:59 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-08-29 13:29:11 -0700 |
| commit | 4eddd2a50f2548c6c83081fde8fdbc3de07626f6 (patch) | |
| tree | 2adb177da1b18471c528e5821850b6d5233f8501 | |
| parent | 2526f368949bccda6e8ed1bf74a4e955e3af42af (diff) | |
| download | lwn-4eddd2a50f2548c6c83081fde8fdbc3de07626f6.tar.gz lwn-4eddd2a50f2548c6c83081fde8fdbc3de07626f6.zip | |
ext4: Resolve the hang of direct i/o read in handling EXT4_IO_END_UNWRITTEN.
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<mjt@tls.msk.ru>
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | fs/ext4/inode.c | 9 | ||||
| -rw-r--r-- | fs/ext4/page-io.c | 6 |
2 files changed, 12 insertions, 3 deletions
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 773de46d7f0c..5390b4da0dd4 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -3645,8 +3645,15 @@ static void ext4_end_io_buffer_write(struct buffer_head *bh, int uptodate) 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); diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c index 7bb8f76d470a..97e5e98fd42a 100644 --- 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)); |