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authorTao Ma <boyu.mt@taobao.com>2011-08-13 12:30:59 -0400
committerTheodore Ts'o <tytso@mit.edu>2011-08-13 12:30:59 -0400
commit32c80b32c053dc52712dedac5e4d0aa7c93fc353 (patch)
tree857375faae2d6c562741d14ed13a1411b197baf5
parent2581fdc810889fdea97689cb62481201d579c796 (diff)
downloadop-kernel-dev-32c80b32c053dc52712dedac5e4d0aa7c93fc353.zip
op-kernel-dev-32c80b32c053dc52712dedac5e4d0aa7c93fc353.tar.gz
ext4: Resolve the hang of direct i/o read in handling EXT4_IO_END_UNWRITTEN.
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> Cc: stable@kernel.org
-rw-r--r--fs/ext4/inode.c9
-rw-r--r--fs/ext4/page-io.c6
2 files changed, 12 insertions, 3 deletions
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 7dd6981..762e803 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2678,8 +2678,15 @@ 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 430c401..78839af 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -334,8 +334,10 @@ 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));
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