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Subject[PATCH 2/2] fs: support direct IO in a multi-device FS
Date
From: Qiuyang Sun <sunqiuyang@huawei.com>

Don't use the bdev pointer in struct buffer_head for dio_bio_alloc(),
since it may have been changed to another device in the FS in
get_more_blocks().

Signed-off-by: Qiuyang Sun <sunqiuyang@huawei.com>
---
fs/direct-io.c | 19 ++++++++++---------
1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/fs/direct-io.c b/fs/direct-io.c
index 722d17c..6cd6029 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -99,6 +99,7 @@ struct dio_submit {
unsigned cur_page_offset; /* Offset into it, in bytes */
unsigned cur_page_len; /* Nr of bytes at cur_page_offset */
sector_t cur_page_block; /* Where it starts */
+ struct block_device *cur_page_dev;
loff_t cur_page_fs_offset; /* Offset in file */

struct iov_iter *iter;
@@ -729,7 +730,7 @@ static int get_more_blocks(struct dio *dio, struct dio_submit *sdio,
* There is no bio. Make one now.
*/
static inline int dio_new_bio(struct dio *dio, struct dio_submit *sdio,
- sector_t start_sector, struct buffer_head *map_bh)
+ sector_t start_sector)
{
sector_t sector;
int ret, nr_pages;
@@ -740,7 +741,7 @@ static inline int dio_new_bio(struct dio *dio, struct dio_submit *sdio,
sector = start_sector << (sdio->blkbits - 9);
nr_pages = min(sdio->pages_in_io, BIO_MAX_PAGES);
BUG_ON(nr_pages <= 0);
- dio_bio_alloc(dio, sdio, map_bh->b_bdev, sector, nr_pages);
+ dio_bio_alloc(dio, sdio, sdio->cur_page_dev, sector, nr_pages);
sdio->boundary = 0;
out:
return ret;
@@ -785,8 +786,7 @@ static inline int dio_bio_add_page(struct dio_submit *sdio)
* The caller of this function is responsible for removing cur_page from the
* dio, and for dropping the refcount which came from that presence.
*/
-static inline int dio_send_cur_page(struct dio *dio, struct dio_submit *sdio,
- struct buffer_head *map_bh)
+static inline int dio_send_cur_page(struct dio *dio, struct dio_submit *sdio)
{
int ret = 0;

@@ -815,14 +815,14 @@ static inline int dio_send_cur_page(struct dio *dio, struct dio_submit *sdio,
}

if (sdio->bio == NULL) {
- ret = dio_new_bio(dio, sdio, sdio->cur_page_block, map_bh);
+ ret = dio_new_bio(dio, sdio, sdio->cur_page_block);
if (ret)
goto out;
}

if (dio_bio_add_page(sdio) != 0) {
dio_bio_submit(dio, sdio);
- ret = dio_new_bio(dio, sdio, sdio->cur_page_block, map_bh);
+ ret = dio_new_bio(dio, sdio, sdio->cur_page_block);
if (ret == 0) {
ret = dio_bio_add_page(sdio);
BUG_ON(ret != 0);
@@ -878,7 +878,7 @@ static inline int dio_send_cur_page(struct dio *dio, struct dio_submit *sdio,
* If there's a deferred page already there then send it.
*/
if (sdio->cur_page) {
- ret = dio_send_cur_page(dio, sdio, map_bh);
+ ret = dio_send_cur_page(dio, sdio);
put_page(sdio->cur_page);
sdio->cur_page = NULL;
if (ret)
@@ -890,6 +890,7 @@ static inline int dio_send_cur_page(struct dio *dio, struct dio_submit *sdio,
sdio->cur_page_offset = offset;
sdio->cur_page_len = len;
sdio->cur_page_block = blocknr;
+ sdio->cur_page_dev = map_bh->b_bdev;
sdio->cur_page_fs_offset = sdio->block_in_file << sdio->blkbits;
out:
/*
@@ -897,7 +898,7 @@ static inline int dio_send_cur_page(struct dio *dio, struct dio_submit *sdio,
* avoid metadata seeks.
*/
if (sdio->boundary) {
- ret = dio_send_cur_page(dio, sdio, map_bh);
+ ret = dio_send_cur_page(dio, sdio);
if (sdio->bio)
dio_bio_submit(dio, sdio);
put_page(sdio->cur_page);
@@ -1348,7 +1349,7 @@ static inline int drop_refcount(struct dio *dio)
if (sdio.cur_page) {
ssize_t ret2;

- ret2 = dio_send_cur_page(dio, &sdio, &map_bh);
+ ret2 = dio_send_cur_page(dio, &sdio);
if (retval == 0)
retval = ret2;
put_page(sdio.cur_page);
--
1.8.3.1
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