From f3714ef479d24d436d8cda0f1011c4001aee409c Mon Sep 17 00:00:00 2001 From: Nikolay Borisov Date: Wed, 12 Dec 2018 09:42:33 +0200 Subject: [PATCH] btrfs: Refactor btrfs_get_extent_fiemap 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 Reviewed-by: David Sterba [ reformatted a few more comments ] Signed-off-by: David Sterba --- fs/btrfs/inode.c | 98 +++++++++++++++++++++++++----------------------- 1 file changed, 51 insertions(+), 47 deletions(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index a35f63691cf8..6a6732b8fcf0 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -6949,10 +6949,10 @@ 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); @@ -6980,80 +6980,84 @@ 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 > 0) { + u64 hole_start; u64 hole_len = len; + const u64 hole_end = extent_map_end(hole_em); em = alloc_extent_map(); if (!em) { err = -ENOMEM; goto out; } - /* - * when btrfs_get_extent can't find anything it - * returns one huge hole - * - * make sure what it found really fits our range, and - * 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; - } - } 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 + + ASSERT(hole_em); + /* + * When btrfs_get_extent can't find anything it returns one + * huge hole + * + * Make sure what it found really fits our range, and adjust to + * make sure it is based on the start from the caller + */ + 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; + } + + 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;