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btrfs: factor out decide_stripe_size()

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Factor out decide_stripe_size() from __btrfs_alloc_chunk(). This
function calculates the actual stripe size to allocate.
decide_stripe_size() handles the common case to round down the 'ndevs'
to 'devs_increment' and check the upper and lower limitation of 'ndevs'.
decide_stripe_size_regular() decides the size of a stripe and the size
of a chunk. The policy is to maximize the number of stripes.

This commit has no functional changes.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Naohiro Aota 2020-02-25 12:56:13 +09:00 committed by David Sterba
parent 560156cb25
commit 5badf512ec
1 changed files with 78 additions and 58 deletions
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136
fs/btrfs/volumes.c
View file

@ -4943,6 +4943,82 @@ static int gather_device_info(struct btrfs_fs_devices *fs_devices,
return 0;
}
static int decide_stripe_size_regular(struct alloc_chunk_ctl *ctl,
struct btrfs_device_info *devices_info)
{
/* Number of stripes that count for block group size */
int data_stripes;
/*
* The primary goal is to maximize the number of stripes, so use as
* many devices as possible, even if the stripes are not maximum sized.
*
* The DUP profile stores more than one stripe per device, the
* max_avail is the total size so we have to adjust.
*/
ctl->stripe_size = div_u64(devices_info[ctl->ndevs - 1].max_avail,
ctl->dev_stripes);
ctl->num_stripes = ctl->ndevs * ctl->dev_stripes;
/* This will have to be fixed for RAID1 and RAID10 over more drives */
data_stripes = (ctl->num_stripes - ctl->nparity) / ctl->ncopies;
/*
* Use the number of data stripes to figure out how big this chunk is
* really going to be in terms of logical address space, and compare
* that answer with the max chunk size. If it's higher, we try to
* reduce stripe_size.
*/
if (ctl->stripe_size * data_stripes > ctl->max_chunk_size) {
/*
* Reduce stripe_size, round it up to a 16MB boundary again and
* then use it, unless it ends up being even bigger than the
* previous value we had already.
*/
ctl->stripe_size = min(round_up(div_u64(ctl->max_chunk_size,
data_stripes), SZ_16M),
ctl->stripe_size);
}
/* Align to BTRFS_STRIPE_LEN */
ctl->stripe_size = round_down(ctl->stripe_size, BTRFS_STRIPE_LEN);
ctl->chunk_size = ctl->stripe_size * data_stripes;
return 0;
}
static int decide_stripe_size(struct btrfs_fs_devices *fs_devices,
struct alloc_chunk_ctl *ctl,
struct btrfs_device_info *devices_info)
{
struct btrfs_fs_info *info = fs_devices->fs_info;
/*
* Round down to number of usable stripes, devs_increment can be any
* number so we can't use round_down() that requires power of 2, while
* rounddown is safe.
*/
ctl->ndevs = rounddown(ctl->ndevs, ctl->devs_increment);
if (ctl->ndevs < ctl->devs_min) {
if (btrfs_test_opt(info, ENOSPC_DEBUG)) {
btrfs_debug(info,
"%s: not enough devices with free space: have=%d minimum required=%d",
__func__, ctl->ndevs, ctl->devs_min);
}
return -ENOSPC;
}
ctl->ndevs = min(ctl->ndevs, ctl->devs_max);
switch (fs_devices->chunk_alloc_policy) {
case BTRFS_CHUNK_ALLOC_REGULAR:
return decide_stripe_size_regular(ctl, devices_info);
default:
BUG();
}
}
static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
u64 start, u64 type)
{
@ -4953,8 +5029,6 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
struct extent_map *em;
struct btrfs_device_info *devices_info = NULL;
struct alloc_chunk_ctl ctl;
/* Number of stripes that count for block group size */
int data_stripes;
int ret;
int i;
int j;
@ -4989,61 +5063,9 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
if (ret < 0)
goto error;
/*
* Round down to number of usable stripes, devs_increment can be any
* number so we can't use round_down()
*/
ctl.ndevs -= ctl.ndevs % ctl.devs_increment;
if (ctl.ndevs < ctl.devs_min) {
ret = -ENOSPC;
if (btrfs_test_opt(info, ENOSPC_DEBUG)) {
btrfs_debug(info,
"%s: not enough devices with free space: have=%d minimum required=%d",
__func__, ctl.ndevs, ctl.devs_min);
}
ret = decide_stripe_size(fs_devices, &ctl, devices_info);
if (ret < 0)
goto error;
}
ctl.ndevs = min(ctl.ndevs, ctl.devs_max);
/*
* The primary goal is to maximize the number of stripes, so use as
* many devices as possible, even if the stripes are not maximum sized.
*
* The DUP profile stores more than one stripe per device, the
* max_avail is the total size so we have to adjust.
*/
ctl.stripe_size = div_u64(devices_info[ctl.ndevs - 1].max_avail,
ctl.dev_stripes);
ctl.num_stripes = ctl.ndevs * ctl.dev_stripes;
/*
* this will have to be fixed for RAID1 and RAID10 over
* more drives
*/
data_stripes = (ctl.num_stripes - ctl.nparity) / ctl.ncopies;
/*
* Use the number of data stripes to figure out how big this chunk
* is really going to be in terms of logical address space,
* and compare that answer with the max chunk size. If it's higher,
* we try to reduce stripe_size.
*/
if (ctl.stripe_size * data_stripes > ctl.max_chunk_size) {
/*
* Reduce stripe_size, round it up to a 16MB boundary again and
* then use it, unless it ends up being even bigger than the
* previous value we had already.
*/
ctl.stripe_size =
min(round_up(div_u64(ctl.max_chunk_size, data_stripes),
SZ_16M),
ctl.stripe_size);
}
/* align to BTRFS_STRIPE_LEN */
ctl.stripe_size = round_down(ctl.stripe_size, BTRFS_STRIPE_LEN);
map = kmalloc(map_lookup_size(ctl.num_stripes), GFP_NOFS);
if (!map) {
@ -5067,8 +5089,6 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
map->type = type;
map->sub_stripes = ctl.sub_stripes;
ctl.chunk_size = ctl.stripe_size * data_stripes;
trace_btrfs_chunk_alloc(info, map, start, ctl.chunk_size);
em = alloc_extent_map();