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btrfs: using cached extent_state in set/unlock combinations
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In several places the sequence (set_extent_uptodate, unlock_extent) is used.
This leads to a duplicate lookup of the extent state. This patch lets
set_extent_uptodate return a cached extent_state which can be passed to
unlock_extent_cached.
The occurences of the above sequences are updated to use the cache. Only
end_bio_extent_readpage is updated that it first gets a cached state to
pass it to the readpage_end_io_hook as the prototype requested and is later
on being used for set/unlock.

Signed-off-by: Arne Jansen <[email protected]>
Signed-off-by: Chris Mason <[email protected]>
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@chrismason-xx
Arne Jansen authored and chrismason-xx committed Apr 12, 2011
1 parent e15d054 commit 507903b
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Showing 3 changed files with 55 additions and 19 deletions.
70 changes: 53 additions & 17 deletions fs/btrfs/extent_io.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -690,6 +690,17 @@ static void cache_state(struct extent_state *state,
}
}

static void uncache_state(struct extent_state **cached_ptr)
{
if (cached_ptr && (*cached_ptr)) {
struct extent_state *state = *cached_ptr;
if (state->state & (EXTENT_IOBITS | EXTENT_BOUNDARY)) {
*cached_ptr = NULL;
free_extent_state(state);
}
}
}

/*
* set some bits on a range in the tree. This may require allocations or
* sleeping, so the gfp mask is used to indicate what is allowed.
Expand Down Expand Up @@ -940,10 +951,10 @@ static int clear_extent_new(struct extent_io_tree *tree, u64 start, u64 end,
}

int set_extent_uptodate(struct extent_io_tree *tree, u64 start, u64 end,
gfp_t mask)
struct extent_state **cached_state, gfp_t mask)
{
return set_extent_bit(tree, start, end, EXTENT_UPTODATE, 0, NULL,
NULL, mask);
return set_extent_bit(tree, start, end, EXTENT_UPTODATE, 0,
NULL, cached_state, mask);
}

static int clear_extent_uptodate(struct extent_io_tree *tree, u64 start,
Expand Down Expand Up @@ -1012,8 +1023,7 @@ int unlock_extent_cached(struct extent_io_tree *tree, u64 start, u64 end,
mask);
}

int unlock_extent(struct extent_io_tree *tree, u64 start, u64 end,
gfp_t mask)
int unlock_extent(struct extent_io_tree *tree, u64 start, u64 end, gfp_t mask)
{
return clear_extent_bit(tree, start, end, EXTENT_LOCKED, 1, 0, NULL,
mask);
Expand Down Expand Up @@ -1735,6 +1745,9 @@ static void end_bio_extent_readpage(struct bio *bio, int err)

do {
struct page *page = bvec->bv_page;
struct extent_state *cached = NULL;
struct extent_state *state;

tree = &BTRFS_I(page->mapping->host)->io_tree;

start = ((u64)page->index << PAGE_CACHE_SHIFT) +
Expand All @@ -1749,9 +1762,20 @@ static void end_bio_extent_readpage(struct bio *bio, int err)
if (++bvec <= bvec_end)
prefetchw(&bvec->bv_page->flags);

spin_lock(&tree->lock);
state = find_first_extent_bit_state(tree, start, 0);
if (state) {
/*
* take a reference on the state, unlock will drop
* the ref
*/
cache_state(state, &cached);
}
spin_unlock(&tree->lock);

if (uptodate && tree->ops && tree->ops->readpage_end_io_hook) {
ret = tree->ops->readpage_end_io_hook(page, start, end,
NULL);
state);
if (ret)
uptodate = 0;
}
Expand All @@ -1764,15 +1788,16 @@ static void end_bio_extent_readpage(struct bio *bio, int err)
test_bit(BIO_UPTODATE, &bio->bi_flags);
if (err)
uptodate = 0;
uncache_state(&cached);
continue;
}
}

if (uptodate) {
set_extent_uptodate(tree, start, end,
set_extent_uptodate(tree, start, end, &cached,
GFP_ATOMIC);
}
unlock_extent(tree, start, end, GFP_ATOMIC);
unlock_extent_cached(tree, start, end, &cached, GFP_ATOMIC);

if (whole_page) {
if (uptodate) {
Expand Down Expand Up @@ -1811,6 +1836,7 @@ static void end_bio_extent_preparewrite(struct bio *bio, int err)

do {
struct page *page = bvec->bv_page;
struct extent_state *cached = NULL;
tree = &BTRFS_I(page->mapping->host)->io_tree;

start = ((u64)page->index << PAGE_CACHE_SHIFT) +
Expand All @@ -1821,13 +1847,14 @@ static void end_bio_extent_preparewrite(struct bio *bio, int err)
prefetchw(&bvec->bv_page->flags);

if (uptodate) {
set_extent_uptodate(tree, start, end, GFP_ATOMIC);
set_extent_uptodate(tree, start, end, &cached,
GFP_ATOMIC);
} else {
ClearPageUptodate(page);
SetPageError(page);
}

unlock_extent(tree, start, end, GFP_ATOMIC);
unlock_extent_cached(tree, start, end, &cached, GFP_ATOMIC);

} while (bvec >= bio->bi_io_vec);

Expand Down Expand Up @@ -2016,14 +2043,17 @@ static int __extent_read_full_page(struct extent_io_tree *tree,
while (cur <= end) {
if (cur >= last_byte) {
char *userpage;
struct extent_state *cached = NULL;

iosize = PAGE_CACHE_SIZE - page_offset;
userpage = kmap_atomic(page, KM_USER0);
memset(userpage + page_offset, 0, iosize);
flush_dcache_page(page);
kunmap_atomic(userpage, KM_USER0);
set_extent_uptodate(tree, cur, cur + iosize - 1,
GFP_NOFS);
unlock_extent(tree, cur, cur + iosize - 1, GFP_NOFS);
&cached, GFP_NOFS);
unlock_extent_cached(tree, cur, cur + iosize - 1,
&cached, GFP_NOFS);
break;
}
em = get_extent(inode, page, page_offset, cur,
Expand Down Expand Up @@ -2063,14 +2093,17 @@ static int __extent_read_full_page(struct extent_io_tree *tree,
/* we've found a hole, just zero and go on */
if (block_start == EXTENT_MAP_HOLE) {
char *userpage;
struct extent_state *cached = NULL;

userpage = kmap_atomic(page, KM_USER0);
memset(userpage + page_offset, 0, iosize);
flush_dcache_page(page);
kunmap_atomic(userpage, KM_USER0);

set_extent_uptodate(tree, cur, cur + iosize - 1,
GFP_NOFS);
unlock_extent(tree, cur, cur + iosize - 1, GFP_NOFS);
&cached, GFP_NOFS);
unlock_extent_cached(tree, cur, cur + iosize - 1,
&cached, GFP_NOFS);
cur = cur + iosize;
page_offset += iosize;
continue;
Expand Down Expand Up @@ -2789,9 +2822,12 @@ int extent_prepare_write(struct extent_io_tree *tree,
iocount++;
block_start = block_start + iosize;
} else {
set_extent_uptodate(tree, block_start, cur_end,
struct extent_state *cached = NULL;

set_extent_uptodate(tree, block_start, cur_end, &cached,
GFP_NOFS);
unlock_extent(tree, block_start, cur_end, GFP_NOFS);
unlock_extent_cached(tree, block_start, cur_end,
&cached, GFP_NOFS);
block_start = cur_end + 1;
}
page_offset = block_start & (PAGE_CACHE_SIZE - 1);
Expand Down Expand Up @@ -3457,7 +3493,7 @@ int set_extent_buffer_uptodate(struct extent_io_tree *tree,
num_pages = num_extent_pages(eb->start, eb->len);

set_extent_uptodate(tree, eb->start, eb->start + eb->len - 1,
GFP_NOFS);
NULL, GFP_NOFS);
for (i = 0; i < num_pages; i++) {
page = extent_buffer_page(eb, i);
if ((i == 0 && (eb->start & (PAGE_CACHE_SIZE - 1))) ||
Expand Down
2 changes: 1 addition & 1 deletion fs/btrfs/extent_io.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -208,7 +208,7 @@ int set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
int bits, int exclusive_bits, u64 *failed_start,
struct extent_state **cached_state, gfp_t mask);
int set_extent_uptodate(struct extent_io_tree *tree, u64 start, u64 end,
gfp_t mask);
struct extent_state **cached_state, gfp_t mask);
int set_extent_new(struct extent_io_tree *tree, u64 start, u64 end,
gfp_t mask);
int set_extent_dirty(struct extent_io_tree *tree, u64 start, u64 end,
Expand Down
2 changes: 1 addition & 1 deletion fs/btrfs/inode.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -5226,7 +5226,7 @@ struct extent_map *btrfs_get_extent(struct inode *inode, struct page *page,
btrfs_mark_buffer_dirty(leaf);
}
set_extent_uptodate(io_tree, em->start,
extent_map_end(em) - 1, GFP_NOFS);
extent_map_end(em) - 1, NULL, GFP_NOFS);
goto insert;
} else {
printk(KERN_ERR "btrfs unknown found_type %d\n", found_type);
Expand Down

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