| Message ID | 1530689092-18090-1-git-send-email-nborisov@suse.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Jul 04, 2018 at 10:24:51AM +0300, Nikolay Borisov wrote: > Current version of the page unlocking code was added in > 727011e07cbd ("Btrfs: allow metadata blocks larger than the page size") > but even in this commit that particular flag was never used per-se. In > fact, btrfs only uses PageChecked for data pages to identify pages > which have been dirtied but don't have ORDERED bit set. For more > information see 247e743cbe6e ("Btrfs: Use async helpers to deal with > pages that have been improperly dirtied"). However, this doesn't apply > to extent buffer pages. The important bit here is that the pages are > unlocked AFTER the extent buffer has been properly recorded in the > radix tree to avoid races with btree_releasepage. Let's exploit this > fact and simplify the page unlocking sequence by unlocking the pages > in-order and removing the redundant PageChecked flag setting/clearing. > > Signed-off-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index d0482832bd6b..2f5c6721d3bc 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -5039,13 +5039,8 @@ struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info, * after the extent buffer is in the radix tree so * it doesn't get lost */ - SetPageChecked(eb->pages[0]); - for (i = 1; i < num_pages; i++) { - p = eb->pages[i]; - ClearPageChecked(p); - unlock_page(p); - } - unlock_page(eb->pages[0]); + for (i = 0; i < num_pages; i++) + unlock_page(eb->pages[i]); return eb; free_eb:
Current version of the page unlocking code was added in 727011e07cbd ("Btrfs: allow metadata blocks larger than the page size") but even in this commit that particular flag was never used per-se. In fact, btrfs only uses PageChecked for data pages to identify pages which have been dirtied but don't have ORDERED bit set. For more information see 247e743cbe6e ("Btrfs: Use async helpers to deal with pages that have been improperly dirtied"). However, this doesn't apply to extent buffer pages. The important bit here is that the pages are unlocked AFTER the extent buffer has been properly recorded in the radix tree to avoid races with btree_releasepage. Let's exploit this fact and simplify the page unlocking sequence by unlocking the pages in-order and removing the redundant PageChecked flag setting/clearing. Signed-off-by: Nikolay Borisov <nborisov@suse.com> --- fs/btrfs/extent_io.c | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-)