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btrfs: Refactor btrfs_calc_avail_data_space

Simplify the code by removing variables that don't bring any real value
as well as simplifying the checks when buidling the candidate list of
devices. No functional changes.

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 2019-07-03 15:32:59 +03:00 committed by David Sterba
parent e678934cbe
commit 559ca6ea69

View File

@ -1899,11 +1899,10 @@ static inline int btrfs_calc_avail_data_space(struct btrfs_fs_info *fs_info,
struct btrfs_device_info *devices_info;
struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
struct btrfs_device *device;
u64 skip_space;
u64 type;
u64 avail_space;
u64 min_stripe_size;
int min_stripes, num_stripes = 1;
int num_stripes = 1;
int i = 0, nr_devices;
const struct btrfs_raid_attr *rattr;
@ -1930,7 +1929,6 @@ static inline int btrfs_calc_avail_data_space(struct btrfs_fs_info *fs_info,
/* calc min stripe number for data space allocation */
type = btrfs_data_alloc_profile(fs_info);
rattr = &btrfs_raid_array[btrfs_bg_flags_to_raid_index(type)];
min_stripes = rattr->devs_min;
if (type & BTRFS_BLOCK_GROUP_RAID0)
num_stripes = nr_devices;
@ -1956,28 +1954,21 @@ static inline int btrfs_calc_avail_data_space(struct btrfs_fs_info *fs_info,
avail_space = device->total_bytes - device->bytes_used;
/* align with stripe_len */
avail_space = div_u64(avail_space, BTRFS_STRIPE_LEN);
avail_space *= BTRFS_STRIPE_LEN;
avail_space = rounddown(avail_space, BTRFS_STRIPE_LEN);
/*
* In order to avoid overwriting the superblock on the drive,
* btrfs starts at an offset of at least 1MB when doing chunk
* allocation.
*
* This ensures we have at least min_stripe_size free space
* after excluding 1MB.
*/
skip_space = SZ_1M;
/*
* we can use the free space in [0, skip_space - 1], subtract
* it from the total.
*/
if (avail_space && avail_space >= skip_space)
avail_space -= skip_space;
else
avail_space = 0;
if (avail_space < min_stripe_size)
if (avail_space <= SZ_1M + min_stripe_size)
continue;
avail_space -= SZ_1M;
devices_info[i].dev = device;
devices_info[i].max_avail = avail_space;
@ -1991,9 +1982,8 @@ static inline int btrfs_calc_avail_data_space(struct btrfs_fs_info *fs_info,
i = nr_devices - 1;
avail_space = 0;
while (nr_devices >= min_stripes) {
if (num_stripes > nr_devices)
num_stripes = nr_devices;
while (nr_devices >= rattr->devs_min) {
num_stripes = min(num_stripes, nr_devices);
if (devices_info[i].max_avail >= min_stripe_size) {
int j;