On Thu, Jul 03, 2014 at 06:22:13PM +0800, Miao Xie wrote: > If we mounted a seed filesystem with degraded option, and then added a new > device into the seed filesystem, then we found adding device failed because > of the IO failure. > > Steps to reproduce: > # mkfs.btrfs -d raid1 -m raid1 <dev0> <dev1> > # btrfstune -S 1 <dev0> > # mount <dev0> -o degraded <mnt> > # btrfs device add -f <dev2> <mnt> > > It is because the original didn't set the chunk on the seed device to be > read-only if the degraded flag was set. It was introduced by patch f48b90756, > which fixed the problem the raid1 filesystem became read-only after one device > of it was missing. But this fix method was not right, we should set the > read-only > flag according to the number of the missing devices, not the degraded mount > option, if the number of the missing devices is less than the max error number > that the profile of the chunk tolerates, we don't set it to be read-only.
Reviewed-by: Liu Bo <bo.li....@oracle.com> -liubo > > Cc: Josef Bacik <jba...@fb.com> > Signed-off-by: Miao Xie <mi...@cn.fujitsu.com> > --- > fs/btrfs/volumes.c | 52 ++++++++++++++++++++++++++++++++++++---------------- > 1 file changed, 36 insertions(+), 16 deletions(-) > > diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c > index 73a82e5..daecfa5 100644 > --- a/fs/btrfs/volumes.c > +++ b/fs/btrfs/volumes.c > @@ -4584,12 +4584,31 @@ out: > return ret; > } > > +static inline int btrfs_chunk_max_errors(struct map_lookup *map) > +{ > + int max_errors; > + > + if (map->type & (BTRFS_BLOCK_GROUP_RAID1 | > + BTRFS_BLOCK_GROUP_RAID10 | > + BTRFS_BLOCK_GROUP_RAID5 | > + BTRFS_BLOCK_GROUP_DUP)) { > + max_errors = 1; > + } else if (map->type & BTRFS_BLOCK_GROUP_RAID6) { > + max_errors = 2; > + } else { > + max_errors = 0; > + } > + > + return max_errors; > +} > + > int btrfs_chunk_readonly(struct btrfs_root *root, u64 chunk_offset) > { > struct extent_map *em; > struct map_lookup *map; > struct btrfs_mapping_tree *map_tree = &root->fs_info->mapping_tree; > int readonly = 0; > + int miss_ndevs = 0; > int i; > > read_lock(&map_tree->map_tree.lock); > @@ -4598,18 +4617,27 @@ int btrfs_chunk_readonly(struct btrfs_root *root, u64 > chunk_offset) > if (!em) > return 1; > > - if (btrfs_test_opt(root, DEGRADED)) { > - free_extent_map(em); > - return 0; > - } > - > map = (struct map_lookup *)em->bdev; > for (i = 0; i < map->num_stripes; i++) { > + if (map->stripes[i].dev->missing) { > + miss_ndevs++; > + continue; > + } > + > if (!map->stripes[i].dev->writeable) { > readonly = 1; > - break; > + goto end; > } > } > + > + /* > + * If the number of missing devices is larger than max errors, > + * we can not write the data into that chunk successfully, so > + * set it readonly. > + */ > + if (miss_ndevs > btrfs_chunk_max_errors(map)) > + readonly = 1; > +end: > free_extent_map(em); > return readonly; > } > @@ -5220,16 +5248,8 @@ static int __btrfs_map_block(struct btrfs_fs_info > *fs_info, int rw, > } > } > > - if (rw & (REQ_WRITE | REQ_GET_READ_MIRRORS)) { > - if (map->type & (BTRFS_BLOCK_GROUP_RAID1 | > - BTRFS_BLOCK_GROUP_RAID10 | > - BTRFS_BLOCK_GROUP_RAID5 | > - BTRFS_BLOCK_GROUP_DUP)) { > - max_errors = 1; > - } else if (map->type & BTRFS_BLOCK_GROUP_RAID6) { > - max_errors = 2; > - } > - } > + if (rw & (REQ_WRITE | REQ_GET_READ_MIRRORS)) > + max_errors = btrfs_chunk_max_errors(map); > > if (dev_replace_is_ongoing && (rw & (REQ_WRITE | REQ_DISCARD)) && > dev_replace->tgtdev != NULL) { > -- > 1.9.3 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html