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Btrfs: ensure an entire eb is written at once
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This patch simplifies how we track our extent buffers.  Previously we could exit
writepages with only having written half of an extent buffer, which meant we had
to track the state of the pages and the state of the extent buffers differently.
Now we only read in entire extent buffers and write out entire extent buffers,
this allows us to simply set bits in our bflags to indicate the state of the eb
and we no longer have to do things like track uptodate with our iotree.  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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Josef Bacik authored and Chris Mason committed Mar 26, 2012
1 parent 5df4235 commit 0b32f4b
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Showing 4 changed files with 390 additions and 209 deletions.
76 changes: 35 additions & 41 deletions fs/btrfs/disk-io.c
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Original file line number Diff line number Diff line change
Expand Up @@ -333,7 +333,7 @@ static int verify_parent_transid(struct extent_io_tree *io_tree,

lock_extent_bits(io_tree, eb->start, eb->start + eb->len - 1,
0, &cached_state, GFP_NOFS);
if (extent_buffer_uptodate(io_tree, eb, cached_state) &&
if (extent_buffer_uptodate(eb) &&
btrfs_header_generation(eb) == parent_transid) {
ret = 0;
goto out;
Expand All @@ -344,7 +344,7 @@ static int verify_parent_transid(struct extent_io_tree *io_tree,
(unsigned long long)parent_transid,
(unsigned long long)btrfs_header_generation(eb));
ret = 1;
clear_extent_buffer_uptodate(io_tree, eb, &cached_state);
clear_extent_buffer_uptodate(eb);
out:
unlock_extent_cached(io_tree, eb->start, eb->start + eb->len - 1,
&cached_state, GFP_NOFS);
Expand Down Expand Up @@ -566,7 +566,12 @@ static int btree_readpage_end_io_hook(struct page *page, u64 start, u64 end,
tree = &BTRFS_I(page->mapping->host)->io_tree;
eb = (struct extent_buffer *)page->private;

reads_done = atomic_dec_and_test(&eb->pages_reading);
/* the pending IO might have been the only thing that kept this buffer
* in memory. Make sure we have a ref for all this other checks
*/
extent_buffer_get(eb);

reads_done = atomic_dec_and_test(&eb->io_pages);
if (!reads_done)
goto err;

Expand Down Expand Up @@ -606,14 +611,17 @@ static int btree_readpage_end_io_hook(struct page *page, u64 start, u64 end,
ret = -EIO;
}

if (!ret)
set_extent_buffer_uptodate(eb);
err:
if (test_bit(EXTENT_BUFFER_READAHEAD, &eb->bflags)) {
clear_bit(EXTENT_BUFFER_READAHEAD, &eb->bflags);
btree_readahead_hook(root, eb, eb->start, ret);
}

if (ret && eb)
clear_extent_buffer_uptodate(tree, eb, NULL);
if (ret)
clear_extent_buffer_uptodate(eb);
free_extent_buffer(eb);
out:
return ret;
}
Expand Down Expand Up @@ -878,20 +886,6 @@ static int btree_migratepage(struct address_space *mapping,
}
#endif

static int btree_writepage(struct page *page, struct writeback_control *wbc)
{
struct extent_io_tree *tree;
tree = &BTRFS_I(page->mapping->host)->io_tree;

if (!(current->flags & PF_MEMALLOC)) {
return extent_write_full_page(tree, page,
btree_get_extent, wbc);
}

redirty_page_for_writepage(wbc, page);
unlock_page(page);
return 0;
}

static int btree_writepages(struct address_space *mapping,
struct writeback_control *wbc)
Expand All @@ -911,7 +905,7 @@ static int btree_writepages(struct address_space *mapping,
if (num_dirty < thresh)
return 0;
}
return extent_writepages(tree, mapping, btree_get_extent, wbc);
return btree_write_cache_pages(mapping, wbc);
}

static int btree_readpage(struct file *file, struct page *page)
Expand Down Expand Up @@ -950,15 +944,28 @@ static void btree_invalidatepage(struct page *page, unsigned long offset)
}
}

static int btree_set_page_dirty(struct page *page)
{
struct extent_buffer *eb;

BUG_ON(!PagePrivate(page));
eb = (struct extent_buffer *)page->private;
BUG_ON(!eb);
BUG_ON(!test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags));
BUG_ON(!atomic_read(&eb->refs));
btrfs_assert_tree_locked(eb);
return __set_page_dirty_nobuffers(page);
}

static const struct address_space_operations btree_aops = {
.readpage = btree_readpage,
.writepage = btree_writepage,
.writepages = btree_writepages,
.releasepage = btree_releasepage,
.invalidatepage = btree_invalidatepage,
#ifdef CONFIG_MIGRATION
.migratepage = btree_migratepage,
#endif
.set_page_dirty = btree_set_page_dirty,
};

int readahead_tree_block(struct btrfs_root *root, u64 bytenr, u32 blocksize,
Expand Down Expand Up @@ -1001,7 +1008,7 @@ int reada_tree_block_flagged(struct btrfs_root *root, u64 bytenr, u32 blocksize,
if (test_bit(EXTENT_BUFFER_CORRUPT, &buf->bflags)) {
free_extent_buffer(buf);
return -EIO;
} else if (extent_buffer_uptodate(io_tree, buf, NULL)) {
} else if (extent_buffer_uptodate(buf)) {
*eb = buf;
} else {
free_extent_buffer(buf);
Expand Down Expand Up @@ -1054,17 +1061,13 @@ struct extent_buffer *read_tree_block(struct btrfs_root *root, u64 bytenr,
return NULL;

ret = btree_read_extent_buffer_pages(root, buf, 0, parent_transid);

if (ret == 0)
set_bit(EXTENT_BUFFER_UPTODATE, &buf->bflags);
return buf;

}

int clean_tree_block(struct btrfs_trans_handle *trans, struct btrfs_root *root,
struct extent_buffer *buf)
{
struct inode *btree_inode = root->fs_info->btree_inode;
if (btrfs_header_generation(buf) ==
root->fs_info->running_transaction->transid) {
btrfs_assert_tree_locked(buf);
Expand All @@ -1080,8 +1083,7 @@ int clean_tree_block(struct btrfs_trans_handle *trans, struct btrfs_root *root,

/* ugh, clear_extent_buffer_dirty needs to lock the page */
btrfs_set_lock_blocking(buf);
clear_extent_buffer_dirty(&BTRFS_I(btree_inode)->io_tree,
buf);
clear_extent_buffer_dirty(buf);
}
return 0;
}
Expand Down Expand Up @@ -1948,6 +1950,7 @@ int open_ctree(struct super_block *sb,
RB_CLEAR_NODE(&BTRFS_I(fs_info->btree_inode)->rb_node);
extent_io_tree_init(&BTRFS_I(fs_info->btree_inode)->io_tree,
fs_info->btree_inode->i_mapping);
BTRFS_I(fs_info->btree_inode)->io_tree.track_uptodate = 0;
extent_map_tree_init(&BTRFS_I(fs_info->btree_inode)->extent_tree);

BTRFS_I(fs_info->btree_inode)->io_tree.ops = &btree_extent_io_ops;
Expand Down Expand Up @@ -3058,8 +3061,7 @@ int btrfs_buffer_uptodate(struct extent_buffer *buf, u64 parent_transid)
int ret;
struct inode *btree_inode = buf->pages[0]->mapping->host;

ret = extent_buffer_uptodate(&BTRFS_I(btree_inode)->io_tree, buf,
NULL);
ret = extent_buffer_uptodate(buf);
if (!ret)
return ret;

Expand All @@ -3070,16 +3072,13 @@ int btrfs_buffer_uptodate(struct extent_buffer *buf, u64 parent_transid)

int btrfs_set_buffer_uptodate(struct extent_buffer *buf)
{
struct inode *btree_inode = buf->pages[0]->mapping->host;
return set_extent_buffer_uptodate(&BTRFS_I(btree_inode)->io_tree,
buf);
return set_extent_buffer_uptodate(buf);
}

void btrfs_mark_buffer_dirty(struct extent_buffer *buf)
{
struct btrfs_root *root = BTRFS_I(buf->pages[0]->mapping->host)->root;
u64 transid = btrfs_header_generation(buf);
struct inode *btree_inode = root->fs_info->btree_inode;
int was_dirty;

btrfs_assert_tree_locked(buf);
Expand All @@ -3091,8 +3090,7 @@ void btrfs_mark_buffer_dirty(struct extent_buffer *buf)
(unsigned long long)root->fs_info->generation);
WARN_ON(1);
}
was_dirty = set_extent_buffer_dirty(&BTRFS_I(btree_inode)->io_tree,
buf);
was_dirty = set_extent_buffer_dirty(buf);
if (!was_dirty) {
spin_lock(&root->fs_info->delalloc_lock);
root->fs_info->dirty_metadata_bytes += buf->len;
Expand Down Expand Up @@ -3147,11 +3145,7 @@ void __btrfs_btree_balance_dirty(struct btrfs_root *root, unsigned long nr)
int btrfs_read_buffer(struct extent_buffer *buf, u64 parent_transid)
{
struct btrfs_root *root = BTRFS_I(buf->pages[0]->mapping->host)->root;
int ret;
ret = btree_read_extent_buffer_pages(root, buf, 0, parent_transid);
if (ret == 0)
set_bit(EXTENT_BUFFER_UPTODATE, &buf->bflags);
return ret;
return btree_read_extent_buffer_pages(root, buf, 0, parent_transid);
}

static int btree_lock_page_hook(struct page *page, void *data,
Expand Down
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