[BUG] fstrim on some btrfs only trims the unallocated space, not trimming any space in existing block groups.
[CAUSE] fstrim_range passed in by default fstrim will be: range->start = 0 range->len = fs_size (which equals with super->total_bytes) range->min_len = 512 However btrfs_trim_fs() following above parameter to search block groups to trim. While it's quite possible that all chunks start beyond super->total_bytes if the fs is balanced several times. In that case, btrfs will skip trimming block groups and only trim the unallocated space of each device. [FIX] For common full fs trimming range passed in, extent its len to (u64)-1 so we will iterate all block groups. And for custom fs trimming range, due to the fact that the range will always be truncated by range [0, super->total_bytes), making custom fs trimming range useless. Just return -ENOTTY for custom fs trimming range. Reported-by: Chris Murphy <[email protected]> Signed-off-by: Qu Wenruo <[email protected]> --- fs/btrfs/extent-tree.c | 29 ++++++++++++++++++++++++----- 1 file changed, 24 insertions(+), 5 deletions(-) diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 3a252d7af158..22bbcc8c4f6c 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -11024,12 +11024,31 @@ int btrfs_trim_fs(struct btrfs_fs_info *fs_info, struct fstrim_range *range) int ret = 0; /* - * try to trim all FS space, our block group may start from non-zero. + * NOTE: Btrfs uses its own logical address space, where its first + * chunk can start anywhere if it wants. + * If we follow common start = 0 and len = fs_size from @range, we + * can end up without trimming any block groups, since it's highly + * possible all chunks start beyond that range. + * + * So if we want to trim the whole fs, extent the len to (u64)-1 to trim + * all block groups. + * + * Also, since @range will always be truncated to fs size, manually + * passing range to trim specified range doesn't make much sense. + * (No mean to trim any block group whose bytenr starts beyond + * @total_bytes) + * So in that case, return -ENOTTY directly to prevent any custom trim + * request. */ - if (range->len == total_bytes) - cache = btrfs_lookup_first_block_group(fs_info, range->start); - else - cache = btrfs_lookup_block_group(fs_info, range->start); + if (range->start == 0 && range->len == total_bytes) { + range->len = (u64)-1; + } else { + btrfs_info(fs_info, + "trimming custom range is not supported due to the limitation of fstrim_range"); + return -ENOTTY; + } + + cache = btrfs_lookup_first_block_group(fs_info, range->start); for (; cache; cache = next_block_group(fs_info, cache)) { if (cache->key.objectid >= (range->start + range->len)) { -- 2.15.0 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
