From 5f1411265e16b257a945a5c9044aecbc7bb99443 Mon Sep 17 00:00:00 2001 From: Nikolay Borisov Date: Mon, 3 Jun 2019 12:05:03 +0300 Subject: [PATCH] btrfs: Introduce btrfs_io_geometry infrastructure Add a structure that holds various parameters for IO calculations and a helper that fills the values. This will help further refactoring and reduction of functions that in some way open-coded the calculations. Signed-off-by: Nikolay Borisov Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/volumes.c | 96 ++++++++++++++++++++++++++++++++++++++++++++++ fs/btrfs/volumes.h | 17 ++++++++ 2 files changed, 113 insertions(+) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 41813813f840..793494690e67 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -5915,6 +5915,102 @@ static bool need_full_stripe(enum btrfs_map_op op) return (op == BTRFS_MAP_WRITE || op == BTRFS_MAP_GET_READ_MIRRORS); } +/* + * btrfs_get_io_geometry - calculates the geomery of a particular (address, len) + * tuple. This information is used to calculate how big a + * particular bio can get before it straddles a stripe. + * + * @fs_info - the filesystem + * @logical - address that we want to figure out the geometry of + * @len - the length of IO we are going to perform, starting at @logical + * @op - type of operation - write or read + * @io_geom - pointer used to return values + * + * Returns < 0 in case a chunk for the given logical address cannot be found, + * usually shouldn't happen unless @logical is corrupted, 0 otherwise. + */ +int btrfs_get_io_geometry(struct btrfs_fs_info *fs_info, enum btrfs_map_op op, + u64 logical, u64 len, struct btrfs_io_geometry *io_geom) +{ + struct extent_map *em; + struct map_lookup *map; + u64 offset; + u64 stripe_offset; + u64 stripe_nr; + u64 stripe_len; + u64 raid56_full_stripe_start = (u64)-1; + int data_stripes; + + ASSERT(op != BTRFS_MAP_DISCARD); + + em = btrfs_get_chunk_map(fs_info, logical, len); + if (IS_ERR(em)) + return PTR_ERR(em); + + map = em->map_lookup; + /* Offset of this logical address in the chunk */ + offset = logical - em->start; + /* Len of a stripe in a chunk */ + stripe_len = map->stripe_len; + /* Stripe wher this block falls in */ + stripe_nr = div64_u64(offset, stripe_len); + /* Offset of stripe in the chunk */ + stripe_offset = stripe_nr * stripe_len; + if (offset < stripe_offset) { + btrfs_crit(fs_info, +"stripe math has gone wrong, stripe_offset=%llu offset=%llu start=%llu logical=%llu stripe_len=%llu", + stripe_offset, offset, em->start, logical, stripe_len); + free_extent_map(em); + return -EINVAL; + } + + /* stripe_offset is the offset of this block in its stripe */ + stripe_offset = offset - stripe_offset; + data_stripes = nr_data_stripes(map); + + if (map->type & BTRFS_BLOCK_GROUP_PROFILE_MASK) { + u64 max_len = stripe_len - stripe_offset; + + /* + * In case of raid56, we need to know the stripe aligned start + */ + if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK) { + unsigned long full_stripe_len = stripe_len * data_stripes; + raid56_full_stripe_start = offset; + + /* + * Allow a write of a full stripe, but make sure we + * don't allow straddling of stripes + */ + raid56_full_stripe_start = div64_u64(raid56_full_stripe_start, + full_stripe_len); + raid56_full_stripe_start *= full_stripe_len; + + /* + * For writes to RAID[56], allow a full stripeset across + * all disks. For other RAID types and for RAID[56] + * reads, just allow a single stripe (on a single disk). + */ + if (op == BTRFS_MAP_WRITE) { + max_len = stripe_len * data_stripes - + (offset - raid56_full_stripe_start); + } + } + len = min_t(u64, em->len - offset, max_len); + } else { + len = em->len - offset; + } + + io_geom->len = len; + io_geom->offset = offset; + io_geom->stripe_len = stripe_len; + io_geom->stripe_nr = stripe_nr; + io_geom->stripe_offset = stripe_offset; + io_geom->raid56_stripe_offset = raid56_full_stripe_start; + + return 0; +} + static int __btrfs_map_block(struct btrfs_fs_info *fs_info, enum btrfs_map_op op, u64 logical, u64 *length, diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h index fea7b65a712e..2a8e398a8742 100644 --- a/fs/btrfs/volumes.h +++ b/fs/btrfs/volumes.h @@ -23,6 +23,21 @@ struct btrfs_pending_bios { struct bio *tail; }; +struct btrfs_io_geometry { + /* remaining bytes before crossing a stripe */ + u64 len; + /* offset of logical address in chunk */ + u64 offset; + /* length of single IO stripe */ + u64 stripe_len; + /* number of stripe where address falls */ + u64 stripe_nr; + /* offset of address in stripe */ + u64 stripe_offset; + /* offset of raid56 stripe into the chunk */ + u64 raid56_stripe_offset; +}; + /* * Use sequence counter to get consistent device stat data on * 32-bit processors. @@ -413,6 +428,8 @@ int btrfs_map_block(struct btrfs_fs_info *fs_info, enum btrfs_map_op op, int btrfs_map_sblock(struct btrfs_fs_info *fs_info, enum btrfs_map_op op, u64 logical, u64 *length, struct btrfs_bio **bbio_ret); +int btrfs_get_io_geometry(struct btrfs_fs_info *fs_info, enum btrfs_map_op op, + u64 logical, u64 len, struct btrfs_io_geometry *io_geom); int btrfs_rmap_block(struct btrfs_fs_info *fs_info, u64 chunk_start, u64 physical, u64 **logical, int *naddrs, int *stripe_len); int btrfs_read_sys_array(struct btrfs_fs_info *fs_info);