btrfs: using cached extent_state in set/unlock combinations

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 <sensille@gmx.net>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 864e049..8dcfb77 100644 (file)
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -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.
@@ -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,
@@ -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);
@@ -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) +
@@ -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;
                }
@@ -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) {
@@ -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) +
@@ -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);
 
@@ -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,
@@ -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;
@@ -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);
@@ -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))) ||

diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index f62c544..af2d717 100644 (file)
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -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,

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index edafc28..5a993e0 100644 (file)
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -5226,7 +5226,7 @@ again:
                        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);