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mpage: add argument structure for do_mpage_readpage()

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Patch series "Submit ->readpages() IO as read-ahead", v4.

The only caller of ->readpages() is from read-ahead, yet we don't submit
IO flagged with REQ_RAHEAD.  This means we don't see it in blktrace, for
instance, which is a shame.  Additionally, it's preventing further
functional changes in the block layer for deadling with read-ahead more
intelligently.  We already make assumptions about ->readpages() just
being for read-ahead in the mpage implementation, using
readahead_gfp_mask(mapping) as out GFP mask of choice.

This small series fixes up mpage_readpages() to submit with REQ_RAHEAD,
which takes care of file systems using mpage_readpages().  The first
patch is a prep patch, that makes do_mpage_readpage() take an argument
structure.

This patch (of 4):

We're currently passing 8 arguments to this function, clean it up a bit
by packing the arguments in an args structure we pass to it.

No intentional functional changes in this patch.

[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/20180621010725.17813-2-axboe@kernel.dk
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Chris Mason <clm@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jens Axboe 2018-08-17 15:45:32 -07:00 committed by Linus Torvalds
parent 87aa752906
commit 357c120652
1 changed files with 57 additions and 52 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

109
fs/mpage.c
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@ -133,6 +133,17 @@ map_buffer_to_page(struct page *page, struct buffer_head *bh, int page_block)
} while (page_bh != head);
}
struct mpage_readpage_args {
struct bio *bio;
struct page *page;
unsigned int nr_pages;
sector_t last_block_in_bio;
struct buffer_head map_bh;
unsigned long first_logical_block;
get_block_t *get_block;
gfp_t gfp;
};
/*
* 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
@ -142,16 +153,14 @@ map_buffer_to_page(struct page *page, struct buffer_head *bh, int page_block)
* 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, struct buffer_head *map_bh,
unsigned long *first_logical_block, get_block_t get_block,
gfp_t gfp)
static struct bio *do_mpage_readpage(struct mpage_readpage_args *args)
{
struct page *page = args->page;
struct inode *inode = page->mapping->host;
const unsigned blkbits = inode->i_blkbits;
const unsigned blocks_per_page = PAGE_SIZE >> blkbits;
const unsigned blocksize = 1 << blkbits;
struct buffer_head *map_bh = &args->map_bh;
sector_t block_in_file;
sector_t last_block;
sector_t last_block_in_file;
@ -168,7 +177,7 @@ do_mpage_readpage(struct bio *bio, struct page *page, unsigned nr_pages,
goto confused;
block_in_file = (sector_t)page->index << (PAGE_SHIFT - blkbits);
last_block = block_in_file + nr_pages * blocks_per_page;
last_block = block_in_file + args->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;
@ -178,9 +187,10 @@ do_mpage_readpage(struct bio *bio, struct page *page, unsigned nr_pages,
* 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;
if (buffer_mapped(map_bh) &&
block_in_file > args->first_logical_block &&
block_in_file < (args->first_logical_block + nblocks)) {
unsigned map_offset = block_in_file - args->first_logical_block;
unsigned last = nblocks - map_offset;
for (relative_block = 0; ; relative_block++) {
@ -208,9 +218,9 @@ do_mpage_readpage(struct bio *bio, struct page *page, unsigned nr_pages,
if (block_in_file < last_block) {
map_bh->b_size = (last_block-block_in_file) << blkbits;
if (get_block(inode, block_in_file, map_bh, 0))
if (args->get_block(inode, block_in_file, map_bh, 0))
goto confused;
*first_logical_block = block_in_file;
args->first_logical_block = block_in_file;
}
if (!buffer_mapped(map_bh)) {
@ -273,43 +283,45 @@ do_mpage_readpage(struct bio *bio, struct page *page, unsigned nr_pages,
/*
* This page will go to BIO. Do we need to send this BIO off first?
*/
if (bio && (*last_block_in_bio != blocks[0] - 1))
bio = mpage_bio_submit(REQ_OP_READ, 0, bio);
if (args->bio && (args->last_block_in_bio != blocks[0] - 1))
args->bio = mpage_bio_submit(REQ_OP_READ, 0, args->bio);
alloc_new:
if (bio == NULL) {
if (args->bio == NULL) {
if (first_hole == blocks_per_page) {
if (!bdev_read_page(bdev, blocks[0] << (blkbits - 9),
page))
goto out;
}
bio = mpage_alloc(bdev, blocks[0] << (blkbits - 9),
min_t(int, nr_pages, BIO_MAX_PAGES), gfp);
if (bio == NULL)
args->bio = mpage_alloc(bdev, blocks[0] << (blkbits - 9),
min_t(int, args->nr_pages,
BIO_MAX_PAGES),
args->gfp);
if (args->bio == NULL)
goto confused;
}
length = first_hole << blkbits;
if (bio_add_page(bio, page, length, 0) < length) {
bio = mpage_bio_submit(REQ_OP_READ, 0, bio);
if (bio_add_page(args->bio, page, length, 0) < length) {
args->bio = mpage_bio_submit(REQ_OP_READ, 0, args->bio);
goto alloc_new;
}
relative_block = block_in_file - *first_logical_block;
relative_block = block_in_file - args->first_logical_block;
nblocks = map_bh->b_size >> blkbits;
if ((buffer_boundary(map_bh) && relative_block == nblocks) ||
(first_hole != blocks_per_page))
bio = mpage_bio_submit(REQ_OP_READ, 0, bio);
args->bio = mpage_bio_submit(REQ_OP_READ, 0, args->bio);
else
*last_block_in_bio = blocks[blocks_per_page - 1];
args->last_block_in_bio = blocks[blocks_per_page - 1];
out:
return bio;
return args->bio;
confused:
if (bio)
bio = mpage_bio_submit(REQ_OP_READ, 0, bio);
if (args->bio)
args->bio = mpage_bio_submit(REQ_OP_READ, 0, args->bio);
if (!PageUptodate(page))
block_read_full_page(page, get_block);
block_read_full_page(page, args->get_block);
else
unlock_page(page);
goto out;
@ -363,15 +375,12 @@ int
mpage_readpages(struct address_space *mapping, struct list_head *pages,
unsigned nr_pages, get_block_t get_block)
{
struct bio *bio = NULL;
struct mpage_readpage_args args = {
.get_block = get_block,
.gfp = readahead_gfp_mask(mapping),
};
unsigned page_idx;
sector_t last_block_in_bio = 0;
struct buffer_head map_bh;
unsigned long first_logical_block = 0;
gfp_t gfp = readahead_gfp_mask(mapping);
map_bh.b_state = 0;
map_bh.b_size = 0;
for (page_idx = 0; page_idx < nr_pages; page_idx++) {
struct page *page = lru_to_page(pages);
@ -379,18 +388,16 @@ mpage_readpages(struct address_space *mapping, struct list_head *pages,
list_del(&page->lru);
if (!add_to_page_cache_lru(page, mapping,
page->index,
gfp)) {
bio = do_mpage_readpage(bio, page,
nr_pages - page_idx,
&last_block_in_bio, &map_bh,
&first_logical_block,
get_block, gfp);
args.gfp)) {
args.page = page;
args.nr_pages = nr_pages - page_idx;
args.bio = do_mpage_readpage(&args);
}
put_page(page);
}
BUG_ON(!list_empty(pages));
if (bio)
mpage_bio_submit(REQ_OP_READ, 0, bio);
if (args.bio)
mpage_bio_submit(REQ_OP_READ, 0, args.bio);
return 0;
}
EXPORT_SYMBOL(mpage_readpages);
@ -400,18 +407,16 @@ EXPORT_SYMBOL(mpage_readpages);
*/
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;
gfp_t gfp = mapping_gfp_constraint(page->mapping, GFP_KERNEL);
struct mpage_readpage_args args = {
.page = page,
.nr_pages = 1,
.get_block = get_block,
.gfp = mapping_gfp_constraint(page->mapping, GFP_KERNEL),
};
map_bh.b_state = 0;
map_bh.b_size = 0;
bio = do_mpage_readpage(bio, page, 1, &last_block_in_bio,
&map_bh, &first_logical_block, get_block, gfp);
if (bio)
mpage_bio_submit(REQ_OP_READ, 0, bio);
args.bio = do_mpage_readpage(&args);
if (args.bio)
mpage_bio_submit(REQ_OP_READ, 0, args.bio);
return 0;
}
EXPORT_SYMBOL(mpage_readpage);