Commit fa30bd05 authored by Badari Pulavarty's avatar Badari Pulavarty Committed by Linus Torvalds

[PATCH] map multiple blocks for mpage_readpages()

This patch changes mpage_readpages() and get_block() to get the disk mapping
information for multiple blocks at the same time.

b_size represents the amount of disk mapping that needs to mapped.  On the
successful get_block() b_size indicates the amount of disk mapping thats
actually mapped.  Only the filesystems who care to use this information and
provide multiple disk blocks at a time can choose to do so.

No changes are needed for the filesystems who wants to ignore this.

[akpm@osdl.org: cleanups]
Signed-off-by: default avatarBadari Pulavarty <pbadari@us.ibm.com>
Cc: Mingming Cao <cmm@us.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent b0cf2321
......@@ -258,7 +258,8 @@ jfs_get_blocks(struct inode *ip, sector_t lblock, unsigned long max_blocks,
static int jfs_get_block(struct inode *ip, sector_t lblock,
struct buffer_head *bh_result, int create)
{
return jfs_get_blocks(ip, lblock, 1, bh_result, create);
return jfs_get_blocks(ip, lblock, bh_result->b_size >> ip->i_blkbits,
bh_result, create);
}
static int jfs_writepage(struct page *page, struct writeback_control *wbc)
......
......@@ -163,9 +163,19 @@ map_buffer_to_page(struct page *page, struct buffer_head *bh, int page_block)
} while (page_bh != head);
}
/*
* This is the worker routine which does all the work of mapping the disk
* blocks and constructs largest possible bios, submits them for IO if the
* blocks are not contiguous on the disk.
*
* We pass a buffer_head back and forth and use its buffer_mapped() flag to
* represent the validity of its disk mapping and to decide when to do the next
* get_block() call.
*/
static struct bio *
do_mpage_readpage(struct bio *bio, struct page *page, unsigned nr_pages,
sector_t *last_block_in_bio, get_block_t get_block)
sector_t *last_block_in_bio, struct buffer_head *map_bh,
unsigned long *first_logical_block, get_block_t get_block)
{
struct inode *inode = page->mapping->host;
const unsigned blkbits = inode->i_blkbits;
......@@ -173,34 +183,72 @@ do_mpage_readpage(struct bio *bio, struct page *page, unsigned nr_pages,
const unsigned blocksize = 1 << blkbits;
sector_t block_in_file;
sector_t last_block;
sector_t last_block_in_file;
sector_t blocks[MAX_BUF_PER_PAGE];
unsigned page_block;
unsigned first_hole = blocks_per_page;
struct block_device *bdev = NULL;
struct buffer_head bh;
int length;
int fully_mapped = 1;
unsigned nblocks;
unsigned relative_block;
if (page_has_buffers(page))
goto confused;
block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits);
last_block = (i_size_read(inode) + blocksize - 1) >> blkbits;
last_block = block_in_file + nr_pages * blocks_per_page;
last_block_in_file = (i_size_read(inode) + blocksize - 1) >> blkbits;
if (last_block > last_block_in_file)
last_block = last_block_in_file;
page_block = 0;
/*
* Map blocks using the result from the previous get_blocks call first.
*/
nblocks = map_bh->b_size >> blkbits;
if (buffer_mapped(map_bh) && block_in_file > *first_logical_block &&
block_in_file < (*first_logical_block + nblocks)) {
unsigned map_offset = block_in_file - *first_logical_block;
unsigned last = nblocks - map_offset;
for (relative_block = 0; ; relative_block++) {
if (relative_block == last) {
clear_buffer_mapped(map_bh);
break;
}
if (page_block == blocks_per_page)
break;
blocks[page_block] = map_bh->b_blocknr + map_offset +
relative_block;
page_block++;
block_in_file++;
}
bdev = map_bh->b_bdev;
}
/*
* Then do more get_blocks calls until we are done with this page.
*/
map_bh->b_page = page;
while (page_block < blocks_per_page) {
map_bh->b_state = 0;
map_bh->b_size = 0;
bh.b_page = page;
for (page_block = 0; page_block < blocks_per_page;
page_block++, block_in_file++) {
bh.b_state = 0;
if (block_in_file < last_block) {
bh.b_size = blocksize;
if (get_block(inode, block_in_file, &bh, 0))
map_bh->b_size = (last_block-block_in_file) << blkbits;
if (get_block(inode, block_in_file, map_bh, 0))
goto confused;
*first_logical_block = block_in_file;
}
if (!buffer_mapped(&bh)) {
if (!buffer_mapped(map_bh)) {
fully_mapped = 0;
if (first_hole == blocks_per_page)
first_hole = page_block;
page_block++;
block_in_file++;
clear_buffer_mapped(map_bh);
continue;
}
......@@ -210,8 +258,8 @@ do_mpage_readpage(struct bio *bio, struct page *page, unsigned nr_pages,
* we just collected from get_block into the page's buffers
* so readpage doesn't have to repeat the get_block call
*/
if (buffer_uptodate(&bh)) {
map_buffer_to_page(page, &bh, page_block);
if (buffer_uptodate(map_bh)) {
map_buffer_to_page(page, map_bh, page_block);
goto confused;
}
......@@ -219,10 +267,20 @@ do_mpage_readpage(struct bio *bio, struct page *page, unsigned nr_pages,
goto confused; /* hole -> non-hole */
/* Contiguous blocks? */
if (page_block && blocks[page_block-1] != bh.b_blocknr-1)
if (page_block && blocks[page_block-1] != map_bh->b_blocknr-1)
goto confused;
blocks[page_block] = bh.b_blocknr;
bdev = bh.b_bdev;
nblocks = map_bh->b_size >> blkbits;
for (relative_block = 0; ; relative_block++) {
if (relative_block == nblocks) {
clear_buffer_mapped(map_bh);
break;
} else if (page_block == blocks_per_page)
break;
blocks[page_block] = map_bh->b_blocknr+relative_block;
page_block++;
block_in_file++;
}
bdev = map_bh->b_bdev;
}
if (first_hole != blocks_per_page) {
......@@ -261,7 +319,7 @@ do_mpage_readpage(struct bio *bio, struct page *page, unsigned nr_pages,
goto alloc_new;
}
if (buffer_boundary(&bh) || (first_hole != blocks_per_page))
if (buffer_boundary(map_bh) || (first_hole != blocks_per_page))
bio = mpage_bio_submit(READ, bio);
else
*last_block_in_bio = blocks[blocks_per_page - 1];
......@@ -332,7 +390,10 @@ mpage_readpages(struct address_space *mapping, struct list_head *pages,
unsigned page_idx;
sector_t last_block_in_bio = 0;
struct pagevec lru_pvec;
struct buffer_head map_bh;
unsigned long first_logical_block = 0;
clear_buffer_mapped(&map_bh);
pagevec_init(&lru_pvec, 0);
for (page_idx = 0; page_idx < nr_pages; page_idx++) {
struct page *page = list_entry(pages->prev, struct page, lru);
......@@ -343,7 +404,9 @@ mpage_readpages(struct address_space *mapping, struct list_head *pages,
page->index, GFP_KERNEL)) {
bio = do_mpage_readpage(bio, page,
nr_pages - page_idx,
&last_block_in_bio, get_block);
&last_block_in_bio, &map_bh,
&first_logical_block,
get_block);
if (!pagevec_add(&lru_pvec, page))
__pagevec_lru_add(&lru_pvec);
} else {
......@@ -365,9 +428,12 @@ int mpage_readpage(struct page *page, get_block_t get_block)
{
struct bio *bio = NULL;
sector_t last_block_in_bio = 0;
struct buffer_head map_bh;
unsigned long first_logical_block = 0;
bio = do_mpage_readpage(bio, page, 1,
&last_block_in_bio, get_block);
clear_buffer_mapped(&map_bh);
bio = do_mpage_readpage(bio, page, 1, &last_block_in_bio,
&map_bh, &first_logical_block, get_block);
if (bio)
mpage_bio_submit(READ, bio);
return 0;
......
......@@ -1310,8 +1310,9 @@ xfs_get_block(
struct buffer_head *bh_result,
int create)
{
return __xfs_get_block(inode, iblock, 0, bh_result,
create, 0, BMAPI_WRITE);
return __xfs_get_block(inode, iblock,
bh_result->b_size >> inode->i_blkbits,
bh_result, create, 0, BMAPI_WRITE);
}
STATIC int
......
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