At 03/13/2017 03:29 PM, Anand Jain wrote:
On 03/09/2017 09:34 AM, 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 <quwen...@cn.fujitsu.com> Signed-off-by: Anand Jain <anand.j...@oracle.com> Tested-by: Austin S. Hemmelgarn <ahferro...@gmail.com> Tested-by: Adam Borowski <kilob...@angband.pl> Tested-by: Dmitrii Tcvetkov <demfl...@demfloro.ru> --- fs/btrfs/volumes.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ fs/btrfs/volumes.h | 1 + 2 files changed, 56 insertions(+) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 73d56eef5e60..83613955e3c2 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -6765,6 +6765,61 @@ 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 the fs is OK to be mounted degraded read-write + * Return false if the fs is not OK to be mounted degraded + */ +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 = (struct map_lookup *) em->bdev;any idea why not map = em->map_lookup; here?
My fault, will update the patch. Thanks, Qu
Thanks, Anand+ max_tolerated = + btrfs_get_num_tolerated_disk_barrier_failures( + map->type); + for (i = 0; i < map->num_stripes; i++) { + if (map->stripes[i].dev->missing) + 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; +} + 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 59be81206dd7..db1b5ef479cf 100644 --- a/fs/btrfs/volumes.h +++ b/fs/btrfs/volumes.h @@ -538,4 +538,5 @@ 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
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