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btrfs: calculate num_pages, reserve_bytes once in btrfs_buffered_write

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write_bytes can change in btrfs_check_nocow_lock(). Calculate variables
such as num_pages and reserve_bytes once we are sure of the value of
write_bytes so there is no need to re-calculate.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Goldwyn Rodrigues 2020-09-25 15:36:38 -05:00 committed by David Sterba
parent fb8a7e941b
commit eefa45f593
1 changed files with 12 additions and 22 deletions
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34
fs/btrfs/file.c
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@ -1591,8 +1591,7 @@ static noinline ssize_t btrfs_buffered_write(struct kiocb *iocb,
size_t write_bytes = min(iov_iter_count(i),
nrptrs * (size_t)PAGE_SIZE -
offset);
size_t num_pages = DIV_ROUND_UP(write_bytes + offset,
PAGE_SIZE);
size_t num_pages;
size_t reserve_bytes;
size_t dirty_pages;
size_t copied;
@ -1600,8 +1599,6 @@ static noinline ssize_t btrfs_buffered_write(struct kiocb *iocb,
size_t num_sectors;
int extents_locked;
WARN_ON(num_pages > nrptrs);
/*
* Fault pages before locking them in prepare_pages
* to avoid recursive lock
@ -1613,35 +1610,28 @@ static noinline ssize_t btrfs_buffered_write(struct kiocb *iocb,
only_release_metadata = false;
sector_offset = pos & (fs_info->sectorsize - 1);
reserve_bytes = round_up(write_bytes + sector_offset,
fs_info->sectorsize);
extent_changeset_release(data_reserved);
ret = btrfs_check_data_free_space(BTRFS_I(inode),
&data_reserved, pos,
write_bytes);
if (ret < 0) {
/*
* If we don't have to COW at the offset, reserve
* metadata only. write_bytes may get smaller than
* requested here.
*/
if (btrfs_check_nocow_lock(BTRFS_I(inode), pos,
&write_bytes) > 0) {
/*
* For nodata cow case, no need to reserve
* data space.
*/
&write_bytes) > 0)
only_release_metadata = true;
/*
* our prealloc extent may be smaller than
* write_bytes, so scale down.
*/
num_pages = DIV_ROUND_UP(write_bytes + offset,
PAGE_SIZE);
reserve_bytes = round_up(write_bytes +
sector_offset,
fs_info->sectorsize);
} else {
else
break;
}
}
num_pages = DIV_ROUND_UP(write_bytes + offset, PAGE_SIZE);
WARN_ON(num_pages > nrptrs);
reserve_bytes = round_up(write_bytes + sector_offset,
fs_info->sectorsize);
WARN_ON(reserve_bytes == 0);
ret = btrfs_delalloc_reserve_metadata(BTRFS_I(inode),
reserve_bytes);