[PATCH 05/11] DIO: Separate map_bh from dio v2
From: Andi Kleen
Date: Tue Aug 02 2011 - 00:39:33 EST
From: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Only a single b_private field in the map_bh buffer head is needed after
the submission path. Move map_bh separately to avoid storing
this information in the long term slab.
This avoids the weird 104 byte hole in struct dio_submit which also needed
to be memseted early.
v2: b_private->private (hch)
Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
---
fs/direct-io.c | 65 +++++++++++++++++++++++++++++++-------------------------
1 files changed, 36 insertions(+), 29 deletions(-)
diff --git a/fs/direct-io.c b/fs/direct-io.c
index e91ac83..172ec77 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -119,6 +119,7 @@ struct dio {
loff_t i_size; /* i_size when submitted */
dio_iodone_t *end_io; /* IO completion function */
+ void *private; /* copy from map_bh.b_private */
/* BIO completion state */
spinlock_t bio_lock; /* protects BIO fields below */
@@ -133,7 +134,6 @@ struct dio {
struct kiocb *iocb; /* kiocb */
ssize_t result; /* IO result */
- struct buffer_head map_bh; /* last get_block() result */
/*
* pages[] (and any fields placed after it) are not zeroed out at
* allocation time. Don't add new fields after pages[] unless you
@@ -301,7 +301,7 @@ static ssize_t dio_complete(struct dio *dio, loff_t offset, ssize_t ret, bool is
if (dio->end_io && dio->result) {
dio->end_io(dio->iocb, offset, transferred,
- dio->map_bh.b_private, ret, is_async);
+ dio->private, ret, is_async);
} else {
if (is_async)
aio_complete(dio->iocb, ret, 0);
@@ -574,10 +574,10 @@ static int dio_bio_reap(struct dio *dio, struct dio_submit *sdio)
* buffer_mapped(). However the direct-io code will only process holes one
* block at a time - it will repeatedly call get_block() as it walks the hole.
*/
-static int get_more_blocks(struct dio *dio, struct dio_submit *sdio)
+static int get_more_blocks(struct dio *dio, struct dio_submit *sdio,
+ struct buffer_head *map_bh)
{
int ret;
- struct buffer_head *map_bh = &dio->map_bh;
sector_t fs_startblk; /* Into file, in filesystem-sized blocks */
unsigned long fs_count; /* Number of filesystem-sized blocks */
unsigned long dio_count;/* Number of dio_block-sized blocks */
@@ -621,6 +621,9 @@ static int get_more_blocks(struct dio *dio, struct dio_submit *sdio)
ret = (*sdio->get_block)(dio->inode, fs_startblk,
map_bh, create);
+
+ /* Store for completion */
+ dio->private = map_bh->b_private;
}
return ret;
}
@@ -629,7 +632,7 @@ static int get_more_blocks(struct dio *dio, struct dio_submit *sdio)
* There is no bio. Make one now.
*/
static int dio_new_bio(struct dio *dio, struct dio_submit *sdio,
- sector_t start_sector)
+ sector_t start_sector, struct buffer_head *map_bh)
{
sector_t sector;
int ret, nr_pages;
@@ -638,10 +641,10 @@ static int dio_new_bio(struct dio *dio, struct dio_submit *sdio,
if (ret)
goto out;
sector = start_sector << (sdio->blkbits - 9);
- nr_pages = min(sdio->pages_in_io, bio_get_nr_vecs(dio->map_bh.b_bdev));
+ nr_pages = min(sdio->pages_in_io, bio_get_nr_vecs(map_bh->b_bdev));
nr_pages = min(nr_pages, BIO_MAX_PAGES);
BUG_ON(nr_pages <= 0);
- dio_bio_alloc(dio, sdio, dio->map_bh.b_bdev, sector, nr_pages);
+ dio_bio_alloc(dio, sdio, map_bh->b_bdev, sector, nr_pages);
sdio->boundary = 0;
out:
return ret;
@@ -686,7 +689,8 @@ static int dio_bio_add_page(struct dio *dio, 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 int dio_send_cur_page(struct dio *dio, struct dio_submit *sdio)
+static int dio_send_cur_page(struct dio *dio, struct dio_submit *sdio,
+ struct buffer_head *map_bh)
{
int ret = 0;
@@ -721,14 +725,14 @@ static 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);
+ ret = dio_new_bio(dio, sdio, sdio->cur_page_block, map_bh);
if (ret)
goto out;
}
if (dio_bio_add_page(dio, sdio) != 0) {
dio_bio_submit(dio, sdio);
- ret = dio_new_bio(dio, sdio, sdio->cur_page_block);
+ ret = dio_new_bio(dio, sdio, sdio->cur_page_block, map_bh);
if (ret == 0) {
ret = dio_bio_add_page(dio, sdio);
BUG_ON(ret != 0);
@@ -757,7 +761,8 @@ out:
*/
static int
submit_page_section(struct dio *dio, struct dio_submit *sdio, struct page *page,
- unsigned offset, unsigned len, sector_t blocknr)
+ unsigned offset, unsigned len, sector_t blocknr,
+ struct buffer_head *map_bh)
{
int ret = 0;
@@ -782,7 +787,7 @@ submit_page_section(struct dio *dio, struct dio_submit *sdio, struct page *page,
* avoid metadata seeks.
*/
if (sdio->boundary) {
- ret = dio_send_cur_page(dio, sdio);
+ ret = dio_send_cur_page(dio, sdio, map_bh);
page_cache_release(sdio->cur_page);
sdio->cur_page = NULL;
}
@@ -793,7 +798,7 @@ submit_page_section(struct dio *dio, struct dio_submit *sdio, struct page *page,
* If there's a deferred page already there then send it.
*/
if (sdio->cur_page) {
- ret = dio_send_cur_page(dio, sdio);
+ ret = dio_send_cur_page(dio, sdio, map_bh);
page_cache_release(sdio->cur_page);
sdio->cur_page = NULL;
if (ret)
@@ -815,16 +820,16 @@ out:
* file blocks. Only called for S_ISREG files - blockdevs do not set
* buffer_new
*/
-static void clean_blockdev_aliases(struct dio *dio)
+static void clean_blockdev_aliases(struct dio *dio, struct buffer_head *map_bh)
{
unsigned i;
unsigned nblocks;
- nblocks = dio->map_bh.b_size >> dio->inode->i_blkbits;
+ nblocks = map_bh->b_size >> dio->inode->i_blkbits;
for (i = 0; i < nblocks; i++) {
- unmap_underlying_metadata(dio->map_bh.b_bdev,
- dio->map_bh.b_blocknr + i);
+ unmap_underlying_metadata(map_bh->b_bdev,
+ map_bh->b_blocknr + i);
}
}
@@ -837,7 +842,8 @@ static void clean_blockdev_aliases(struct dio *dio)
* `end' is zero if we're doing the start of the IO, 1 at the end of the
* IO.
*/
-static void dio_zero_block(struct dio *dio, struct dio_submit *sdio, int end)
+static void dio_zero_block(struct dio *dio, struct dio_submit *sdio, int end,
+ struct buffer_head *map_bh)
{
unsigned dio_blocks_per_fs_block;
unsigned this_chunk_blocks; /* In dio_blocks */
@@ -845,7 +851,7 @@ static void dio_zero_block(struct dio *dio, struct dio_submit *sdio, int end)
struct page *page;
sdio->start_zero_done = 1;
- if (!sdio->blkfactor || !buffer_new(&dio->map_bh))
+ if (!sdio->blkfactor || !buffer_new(map_bh))
return;
dio_blocks_per_fs_block = 1 << sdio->blkfactor;
@@ -865,7 +871,7 @@ static void dio_zero_block(struct dio *dio, struct dio_submit *sdio, int end)
page = ZERO_PAGE(0);
if (submit_page_section(dio, sdio, page, 0, this_chunk_bytes,
- sdio->next_block_for_io))
+ sdio->next_block_for_io, map_bh))
return;
sdio->next_block_for_io += this_chunk_blocks;
@@ -887,13 +893,13 @@ static void dio_zero_block(struct dio *dio, struct dio_submit *sdio, int end)
* it should set b_size to PAGE_SIZE or more inside get_block(). This gives
* fine alignment but still allows this function to work in PAGE_SIZE units.
*/
-static int do_direct_IO(struct dio *dio, struct dio_submit *sdio)
+static int do_direct_IO(struct dio *dio, struct dio_submit *sdio,
+ struct buffer_head *map_bh)
{
const unsigned blkbits = sdio->blkbits;
const unsigned blocks_per_page = PAGE_SIZE >> blkbits;
struct page *page;
unsigned block_in_page;
- struct buffer_head *map_bh = &dio->map_bh;
int ret = 0;
/* The I/O can start at any block offset within the first page */
@@ -919,7 +925,7 @@ static int do_direct_IO(struct dio *dio, struct dio_submit *sdio)
unsigned long blkmask;
unsigned long dio_remainder;
- ret = get_more_blocks(dio, sdio);
+ ret = get_more_blocks(dio, sdio, map_bh);
if (ret) {
page_cache_release(page);
goto out;
@@ -932,7 +938,7 @@ static int do_direct_IO(struct dio *dio, struct dio_submit *sdio)
sdio->next_block_for_io =
map_bh->b_blocknr << sdio->blkfactor;
if (buffer_new(map_bh))
- clean_blockdev_aliases(dio);
+ clean_blockdev_aliases(dio, map_bh);
if (!sdio->blkfactor)
goto do_holes;
@@ -991,7 +997,7 @@ do_holes:
* we must zero out the start of this block.
*/
if (unlikely(sdio->blkfactor && !sdio->start_zero_done))
- dio_zero_block(dio, sdio, 0);
+ dio_zero_block(dio, sdio, 0, map_bh);
/*
* Work out, in this_chunk_blocks, how much disk we
@@ -1009,7 +1015,7 @@ do_holes:
sdio->boundary = buffer_boundary(map_bh);
ret = submit_page_section(dio, sdio, page, offset_in_page,
- this_chunk_bytes, sdio->next_block_for_io);
+ this_chunk_bytes, sdio->next_block_for_io, map_bh);
if (ret) {
page_cache_release(page);
goto out;
@@ -1045,6 +1051,7 @@ direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode,
ssize_t ret = 0;
ssize_t ret2;
size_t bytes;
+ struct buffer_head map_bh = { 0, };
dio->inode = inode;
dio->rw = rw;
@@ -1099,7 +1106,7 @@ direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode,
sdio->total_pages += (bytes + PAGE_SIZE - 1) / PAGE_SIZE;
sdio->curr_user_address = user_addr;
- ret = do_direct_IO(dio, sdio);
+ ret = do_direct_IO(dio, sdio, &map_bh);
dio->result += iov[seg].iov_len -
((sdio->final_block_in_request - sdio->block_in_file) <<
@@ -1122,10 +1129,10 @@ direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode,
* There may be some unwritten disk at the end of a part-written
* fs-block-sized block. Go zero that now.
*/
- dio_zero_block(dio, sdio, 1);
+ dio_zero_block(dio, sdio, 1, &map_bh);
if (sdio->cur_page) {
- ret2 = dio_send_cur_page(dio, sdio);
+ ret2 = dio_send_cur_page(dio, sdio, &map_bh);
if (ret == 0)
ret = ret2;
page_cache_release(sdio->cur_page);
--
1.7.4.4
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