On Wed, Dec 12, 2018 at 09:42:33AM +0200, Nikolay Borisov wrote:
> Make btrfs_get_extent_fiemap a bit more friendly. First step is to
> rename the closely related, yet arbitrary named
> range_start/found_end/found variables. They define the delalloc range
> that is found in case a real extent wasn't found. Subsequently remove
> an unnecessary check for hole_em since it's guaranteed to be set i.e the
> check is always true. Top it off by giving all comments a refresh.
>
> No functional changes.
>
> Signed-off-by: Nikolay Borisov <nborisov@xxxxxxxx>
Reviewed-by: David Sterba <dsterba@xxxxxxxx>
> ---
> fs/btrfs/inode.c | 84 ++++++++++++++++++++++++++----------------------
> 1 file changed, 45 insertions(+), 39 deletions(-)
>
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index 67eee4d345c9..95eb18779c19 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -6965,10 +6965,10 @@ struct extent_map *btrfs_get_extent_fiemap(struct btrfs_inode *inode,
> {
> struct extent_map *em;
> struct extent_map *hole_em = NULL;
> - u64 range_start = start;
> + u64 delalloc_start = start;
> u64 end;
> - u64 found;
> - u64 found_end;
> + u64 delalloc_len;
> + u64 delalloc_end;
> int err = 0;
>
> em = btrfs_get_extent(inode, NULL, 0, start, len, 0);
> @@ -6996,37 +6996,42 @@ struct extent_map *btrfs_get_extent_fiemap(struct btrfs_inode *inode,
> em = NULL;
>
> /* ok, we didn't find anything, lets look for delalloc */
> - found = count_range_bits(&inode->io_tree, &range_start,
> + delalloc_len = count_range_bits(&inode->io_tree, &delalloc_start,
> end, len, EXTENT_DELALLOC, 1);
> - found_end = range_start + found;
> - if (found_end < range_start)
> - found_end = (u64)-1;
> + delalloc_end = delalloc_start + delalloc_len;
> + if (delalloc_end < delalloc_start)
> + delalloc_end = (u64)-1;
>
> /*
> - * we didn't find anything useful, return
> - * the original results from get_extent()
> + * we didn't find anything useful, return the original results from
> + * get_extent()
> */
> - if (range_start > end || found_end <= start) {
> + if (delalloc_start > end || delalloc_end <= start) {
> em = hole_em;
> hole_em = NULL;
> goto out;
> }
>
> - /* adjust the range_start to make sure it doesn't
> - * go backwards from the start they passed in
> + /*
> + * adjust the delalloc_start to make sure it doesn't go backwards from
> + * the start they passed in
> */
> - range_start = max(start, range_start);
> - found = found_end - range_start;
> + delalloc_start = max(start, delalloc_start);
> + delalloc_len = delalloc_end - delalloc_start;
>
> - if (found > 0) {
> - u64 hole_start = start;
> + if (delalloc_len) {
> + u64 hole_start;
> u64 hole_len = len;
> + u64 hole_end = extent_map_end(hole_em);
>
> em = alloc_extent_map();
> if (!em) {
> err = -ENOMEM;
> goto out;
> }
> + em->bdev = NULL;
> +
> + ASSERT(hole_em);
> /*
> * when btrfs_get_extent can't find anything it
> * returns one huge hole
> @@ -7035,41 +7040,42 @@ struct extent_map *btrfs_get_extent_fiemap(struct btrfs_inode *inode,
> * adjust to make sure it is based on the start from
> * the caller
> */
> - if (hole_em) {
> - u64 calc_end = extent_map_end(hole_em);
> -
> - if (calc_end <= start || (hole_em->start > end)) {
> - free_extent_map(hole_em);
> - hole_em = NULL;
> - } else {
> - hole_start = max(hole_em->start, start);
> - hole_len = calc_end - hole_start;
> - }
> + if (hole_end <= start || (hole_em->start > end)) {
> + free_extent_map(hole_em);
> + hole_em = NULL;
> + } else {
> + hole_start = max(hole_em->start, start);
> + hole_len = hole_end - hole_start;
> }
> - em->bdev = NULL;
> - if (hole_em && range_start > hole_start) {
> - /* our hole starts before our delalloc, so we
> - * have to return just the parts of the hole
> - * that go until the delalloc starts
> +
> + if (hole_em && delalloc_start > hole_start) {
> + /*
> + * our hole starts before our delalloc, so we have to
> + * return just the parts of the hole that go until the
> + * delalloc starts
> */
> - em->len = min(hole_len,
> - range_start - hole_start);
> + em->len = min(hole_len, delalloc_start - hole_start);
> em->start = hole_start;
> em->orig_start = hole_start;
> /*
> - * don't adjust block start at all,
> - * it is fixed at EXTENT_MAP_HOLE
> + * don't adjust block start at all, it is fixed at
> + * EXTENT_MAP_HOLE
> */
> em->block_start = hole_em->block_start;
> em->block_len = hole_len;
> if (test_bit(EXTENT_FLAG_PREALLOC, &hole_em->flags))
> set_bit(EXTENT_FLAG_PREALLOC, &em->flags);
> } else {
> - em->start = range_start;
> - em->len = found;
> - em->orig_start = range_start;
> +
> + /*
> + * Hole is out of passed range or it starts after
> + * delalloc range
> + */
> + em->start = delalloc_start;
> + em->len = delalloc_len;
> + em->orig_start = delalloc_start;
> em->block_start = EXTENT_MAP_DELALLOC;
> - em->block_len = found;
> + em->block_len = delalloc_len;
> }
> } else {
> return hole_em;
> --
> 2.17.1
