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btrfs: Introduce btrfs_io_geometry infrastructure

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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 <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Nikolay Borisov 2019-06-03 12:05:03 +03:00 committed by David Sterba
parent c9d713d5b5
commit 5f1411265e
2 changed files with 113 additions and 0 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

96
fs/btrfs/volumes.c
View file

@ -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,

17
fs/btrfs/volumes.h
View file

@ -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);