From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.suse.de ([195.135.220.15]:44557 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750917AbdGNHoY (ORCPT ); Fri, 14 Jul 2017 03:44:24 -0400 Subject: Re: [PATCH v4 1/6] btrfs: Introduce a function to check if all chunks a OK for degraded rw mount To: Qu Wenruo , linux-btrfs@vger.kernel.org, dsterba@suse.cz Cc: ahferroin7@gmail.com, kilobyte@angband.pl, demfloro@demfloro.ru, Anand Jain References: <20170628054335.18806-1-quwenruo@cn.fujitsu.com> <20170628054335.18806-2-quwenruo@cn.fujitsu.com> From: Nikolay Borisov Message-ID: Date: Fri, 14 Jul 2017 10:44:20 +0300 MIME-Version: 1.0 In-Reply-To: <20170628054335.18806-2-quwenruo@cn.fujitsu.com> Content-Type: text/plain; charset=utf-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 28.06.2017 08:43, Qu Wenruo wrote: > Introduce a new function, btrfs_check_rw_degradable(), to check if all > chunks in btrfs is OK for degraded rw mount. > > It provides the new basis for accurate btrfs mount/remount and even > runtime degraded mount check other than old one-size-fit-all method. > > Signed-off-by: Qu Wenruo > Signed-off-by: Anand Jain > --- > fs/btrfs/volumes.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ > fs/btrfs/volumes.h | 1 + > 2 files changed, 59 insertions(+) > > diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c > index c95f018d4a1e..7a72fbdb8262 100644 > --- a/fs/btrfs/volumes.c > +++ b/fs/btrfs/volumes.c > @@ -6817,6 +6817,64 @@ int btrfs_read_sys_array(struct btrfs_fs_info *fs_info) > return -EIO; > } > > +/* > + * Check if all chunks in the fs is OK for read-write degraded mount > + * > + * Return true if all chunks meet the minimal RW mount requirement. > + * Return false if any chunk doesn't meet the minimal RW mount requirement. > + */ > +bool btrfs_check_rw_degradable(struct btrfs_fs_info *fs_info) > +{ > + struct btrfs_mapping_tree *map_tree = &fs_info->mapping_tree; > + struct extent_map *em; > + u64 next_start = 0; > + bool ret = true; > + > + read_lock(&map_tree->map_tree.lock); > + em = lookup_extent_mapping(&map_tree->map_tree, 0, (u64)-1); > + read_unlock(&map_tree->map_tree.lock); > + /* No chunk at all? Return false anyway */ > + if (!em) { > + ret = false; > + goto out; > + } > + while (em) { > + struct map_lookup *map; > + int missing = 0; > + int max_tolerated; > + int i; > + > + map = em->map_lookup; > + max_tolerated = > + btrfs_get_num_tolerated_disk_barrier_failures( > + map->type); > + for (i = 0; i < map->num_stripes; i++) { > + struct btrfs_device *dev = map->stripes[i].dev; > + > + if (!dev || !dev->bdev || dev->missing || > + dev->last_flush_error) > + missing++; > + } > + if (missing > max_tolerated) { > + ret = false; > + btrfs_warn(fs_info, > + "chunk %llu missing %d devices, max tolerance is %d for writeble mount", > + em->start, missing, max_tolerated); > + free_extent_map(em); > + goto out; > + } > + next_start = extent_map_end(em); > + free_extent_map(em); > + > + read_lock(&map_tree->map_tree.lock); > + em = lookup_extent_mapping(&map_tree->map_tree, next_start, > + (u64)(-1) - next_start); > + read_unlock(&map_tree->map_tree.lock); > + } > +out: > + return ret; > +} > + Nit but I think in this function it would be best to directly return true/false based on context rather than having the superfluous goto. > int btrfs_read_chunk_tree(struct btrfs_fs_info *fs_info) > { > struct btrfs_root *root = fs_info->chunk_root; > diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h > index 6f45fd60d15a..a5897c7a7e86 100644 > --- a/fs/btrfs/volumes.h > +++ b/fs/btrfs/volumes.h > @@ -543,4 +543,5 @@ struct list_head *btrfs_get_fs_uuids(void); > void btrfs_set_fs_info_ptr(struct btrfs_fs_info *fs_info); > void btrfs_reset_fs_info_ptr(struct btrfs_fs_info *fs_info); > > +bool btrfs_check_rw_degradable(struct btrfs_fs_info *fs_info); > #endif >