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Date: Mon, 24 Dec 2012 15:55:41 +0800
From: Zheng Liu <gnehzuil.liu@...il.com>
To: linux-ext4@...r.kernel.org
Cc: Jan Kara <jack@...e.cz>,
"Darrick J. Wong" <darrick.wong@...cle.com>,
Christoph Hellwig <hch@...radead.org>,
Zheng Liu <wenqing.lz@...bao.com>
Subject: [RFC][PATCH 8/9 v1] ext4: refine unwritten extent conversion
From: Zheng Liu <wenqing.lz@...bao.com>
Currently all unwritten extent conversion work is pushed into a workqueue to be
done because DIO end_io is in a irq context and this conversion needs to take
i_data_sem locking. But we couldn't take a semaphore in a irq context. After
tracking all extent status, we can first convert this unwritten extent in extent
status tree, and call aio_complete() and inode_dio_done() to notify upper level
that this dio has done. We don't need to be worried about exposing a stale data
because we first try to lookup in extent status tree. So it makes us to see the
latest extent status. Meanwhile we queue a work to convert this unwritten
extent in extent tree. After this improvement, reader also needn't wait this
conversion to be done when dioread_nolock is enabled.
CC: Jan Kara <jack@...e.cz>
CC: "Darrick J. Wong" <darrick.wong@...cle.com>
CC: Christoph Hellwig <hch@...radead.org>
Signed-off-by: Zheng Liu <wenqing.lz@...bao.com>
---
[Cc' to Jan, Darrick, and Christoph because Christoph is trying to handle
O_(D)SYNC for AIO]
Hi Jan, Darrick, and Christoph,
This patch refines the unwritten extent conversion in ext4. Now we can call
aio_complete() and inode_dio_done() in end_io function. I believe Christoph's
patch also can work well after applied this patch. Could you please review
this patch?
Regards,
- Zheng
fs/ext4/ext4.h | 2 +-
fs/ext4/indirect.c | 11 ++++-------
fs/ext4/inode.c | 11 ++++-------
fs/ext4/page-io.c | 26 ++++++++++++++++++++++----
4 files changed, 31 insertions(+), 19 deletions(-)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 8462eb3..b76dc49 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -195,7 +195,6 @@ struct mpage_da_data {
#define EXT4_IO_END_UNWRITTEN 0x0001
#define EXT4_IO_END_ERROR 0x0002
#define EXT4_IO_END_QUEUED 0x0004
-#define EXT4_IO_END_DIRECT 0x0008
struct ext4_io_page {
struct page *p_page;
@@ -2538,6 +2537,7 @@ extern void ext4_ioend_wait(struct inode *);
extern void ext4_free_io_end(ext4_io_end_t *io);
extern ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags);
extern void ext4_io_submit(struct ext4_io_submit *io);
+extern void ext4_end_io_bh(ext4_io_end_t *io_end, int is_dio);
extern int ext4_bio_write_page(struct ext4_io_submit *io,
struct page *page,
int len,
diff --git a/fs/ext4/indirect.c b/fs/ext4/indirect.c
index 20862f9..c6d7f7f 100644
--- a/fs/ext4/indirect.c
+++ b/fs/ext4/indirect.c
@@ -807,11 +807,6 @@ ssize_t ext4_ind_direct_IO(int rw, struct kiocb *iocb,
retry:
if (rw == READ && ext4_should_dioread_nolock(inode)) {
- if (unlikely(atomic_read(&EXT4_I(inode)->i_unwritten))) {
- mutex_lock(&inode->i_mutex);
- ext4_flush_unwritten_io(inode);
- mutex_unlock(&inode->i_mutex);
- }
/*
* Nolock dioread optimization may be dynamically disabled
* via ext4_inode_block_unlocked_dio(). Check inode's state
@@ -831,8 +826,10 @@ retry:
inode_dio_done(inode);
} else {
locked:
- ret = blockdev_direct_IO(rw, iocb, inode, iov,
- offset, nr_segs, ext4_get_block);
+ ret = __blockdev_direct_IO(rw, iocb, inode,
+ inode->i_sb->s_bdev, iov,
+ offset, nr_segs,
+ ext4_get_block, NULL, NULL, DIO_LOCKING);
if (unlikely((rw & WRITE) && ret < 0)) {
loff_t isize = i_size_read(inode);
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 6610dc7..4549103 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3024,9 +3024,8 @@ static int ext4_get_block_write_nolock(struct inode *inode, sector_t iblock,
EXT4_GET_BLOCKS_NO_LOCK);
}
-static void ext4_end_io_dio(struct kiocb *iocb, loff_t offset,
- ssize_t size, void *private, int ret,
- bool is_async)
+static void ext4_end_dio(struct kiocb *iocb, loff_t offset, ssize_t size,
+ void *private, int ret, bool is_async)
{
struct inode *inode = iocb->ki_filp->f_path.dentry->d_inode;
ext4_io_end_t *io_end = iocb->private;
@@ -3058,8 +3057,7 @@ out:
io_end->iocb = iocb;
io_end->result = ret;
}
-
- ext4_add_complete_io(io_end);
+ ext4_end_io_bh(io_end, 1);
}
static void ext4_end_io_buffer_write(struct buffer_head *bh, int uptodate)
@@ -3195,7 +3193,6 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
ret = -ENOMEM;
goto retake_lock;
}
- io_end->flag |= EXT4_IO_END_DIRECT;
iocb->private = io_end;
/*
* we save the io structure for current async direct
@@ -3216,7 +3213,7 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
inode->i_sb->s_bdev, iov,
offset, nr_segs,
get_block_func,
- ext4_end_io_dio,
+ ext4_end_dio,
NULL,
dio_flags);
diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index 0016fbc..6b2d88d 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -103,17 +103,35 @@ static int ext4_end_io(ext4_io_end_t *io)
"(inode %lu, offset %llu, size %zd, error %d)",
inode->i_ino, offset, size, ret);
}
- if (io->iocb)
- aio_complete(io->iocb, io->result, 0);
- if (io->flag & EXT4_IO_END_DIRECT)
- inode_dio_done(inode);
/* Wake up anyone waiting on unwritten extent conversion */
if (atomic_dec_and_test(&EXT4_I(inode)->i_unwritten))
wake_up_all(ext4_ioend_wq(inode));
+
return ret;
}
+void ext4_end_io_bh(ext4_io_end_t *io_end, int is_dio)
+{
+ struct inode *inode;
+
+ inode = io_end->inode;
+ (void)ext4_es_convert_unwritten_extents(inode, io_end->offset,
+ io_end->size);
+ ext4_add_complete_io(io_end);
+
+ /*
+ * Here we can safely notify upper level that aio has done because
+ * unwritten extent in extent status tree has been converted. Thus,
+ * others won't get a stale data because we always lookup extent status
+ * tree firstly in get_block_t.
+ */
+ if (io_end->iocb)
+ aio_complete(io_end->iocb, io_end->result, 0);
+ if (is_dio)
+ inode_dio_done(inode);
+}
+
static void dump_completed_IO(struct inode *inode)
{
#ifdef EXT4FS_DEBUG
--
1.7.12.rc2.18.g61b472e
--
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