Btrfs: add direct I/O helper routines to decode em map_lookup.
RFC PATCH 8/12 Btrfs: add direct I/O helper routines to decode em map_lookup.
Direct I/O needs the total number of block devices and the struct block_device for each to allocate control structures prior to building bios for an extent. When building a bio, the device's base physical address of the chunk is needed.
Signed-off-by jim owens <[email protected]>
--- fs/btrfs/volumes.c | 15 +++++++++++++++ fs/btrfs/volumes.h | 3 +++ 2 files changed, 18 insertions(+), 0 deletions(-)
fs/btrfs/volumes.c +15 -0
@@ -2614,6 +2614,21 @@ static int find_live_mirror(struct map_lookup *map, int first, int num,return optimal; } +int btrfs_map_stripe_count (struct extent_map *em) +{ +return ((struct map_lookup *)em->bdev)->num_stripes; +} + +struct block_device *btrfs_map_stripe_bdev (struct extent_map *em,int stripe) +{ +return ((struct map_lookup *)em->bdev)->stripes[stripe].dev->bdev; +} + +u64 btrfs_map_stripe_physical (struct extent_map *em,int stripe) +{ +return ((struct map_lookup *)em->bdev)->stripes[stripe].physical; +} +void btrfs_map_to_stripe (struct extent_map *em,int rw,int mirror_num,u64 logical,u64 *length,struct btrfs_stripe_info *stripe_info)
fs/btrfs/volumes.h +3 -0
@@ -192,4 +192,7 @@ int btrfs_chunk_readonly(struct btrfs_root *root, u64 chunk_offset);int find_free_dev_extent (struct btrfs_trans_handle *trans,struct btrfs_device *device,u64 num_bytes,u64 *start,u64 *max_avail); +int btrfs_map_stripe_count (struct extent_map *em); +struct block_device *btrfs_map_stripe_bdev (struct extent_map *em,int stripe); +u64 btrfs_map_stripe_physical (struct extent_map *em,int stripe);#endif
Signature · 1 line
1.5.6.3