Btrfs: don't lock bits in the extent tree during writepage

At writepage time, we have the page locked and we have the
extent_map entry for this extent pinned in the extent_map tree.
So, the page can't go away and its mapping can't change.

There is no need for the extra extent_state lock bits during writepage.

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

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index c7a5e860fe2151cb6155c4981f2e27e1a5800118..04fafc3cffc0e20d7e0fdaa6b6317db223430d77 100644 (file)
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2219,16 +2219,10 @@ static int __extent_writepage(struct page *page, struct writeback_control *wbc,
                        goto done_unlocked;
                }
        }
-       lock_extent_bits(tree, start, page_end, 0, &cached_state, GFP_NOFS);
-
-       unlock_start = start;
-
        if (tree->ops && tree->ops->writepage_start_hook) {
                ret = tree->ops->writepage_start_hook(page, start,
                                                      page_end);
                if (ret == -EAGAIN) {
-                       unlock_extent_cached(tree, start, page_end,
-                                            &cached_state, GFP_NOFS);
                        redirty_page_for_writepage(wbc, page);
                        update_nr_written(page, wbc, nr_written);
                        unlock_page(page);
@@ -2244,13 +2238,7 @@ static int __extent_writepage(struct page *page, struct writeback_control *wbc,
        update_nr_written(page, wbc, nr_written + 1);
 
        end = page_end;
-       if (test_range_bit(tree, start, page_end, EXTENT_DELALLOC, 0))
-               printk(KERN_ERR "btrfs delalloc bits after lock_extent\n");
-
        if (last_byte <= start) {
-               clear_extent_bit(tree, start, page_end,
-                                EXTENT_LOCKED | EXTENT_DIRTY,
-                                1, 0, NULL, GFP_NOFS);
                if (tree->ops && tree->ops->writepage_end_io_hook)
                        tree->ops->writepage_end_io_hook(page, start,
                                                         page_end, NULL, 1);
@@ -2262,8 +2250,6 @@ static int __extent_writepage(struct page *page, struct writeback_control *wbc,
 
        while (cur <= end) {
                if (cur >= last_byte) {
-                       unlock_extent_cached(tree, unlock_start, page_end,
-                                            &cached_state, GFP_NOFS);
                        if (tree->ops && tree->ops->writepage_end_io_hook)
                                tree->ops->writepage_end_io_hook(page, cur,
                                                         page_end, NULL, 1);
@@ -2295,10 +2281,6 @@ static int __extent_writepage(struct page *page, struct writeback_control *wbc,
                 */
                if (compressed || block_start == EXTENT_MAP_HOLE ||
                    block_start == EXTENT_MAP_INLINE) {
-                       unlock_extent_cached(tree, unlock_start,
-                                            cur + iosize - 1, &cached_state,
-                                            GFP_NOFS);
-
                        /*
                         * end_io notification does not happen here for
                         * compressed extents
@@ -2366,9 +2348,6 @@ done:
                set_page_writeback(page);
                end_page_writeback(page);
        }
-       if (unlock_start <= page_end)
-               unlock_extent_cached(tree, unlock_start, page_end,
-                                    &cached_state, GFP_NOFS);
        unlock_page(page);
 
 done_unlocked: