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| author | Qu Wenruo <wqu@suse.com> | 2022-06-13 10:06:34 +0300 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2022-07-25 18:45:36 +0300 |
| commit | 37f85ec320e6d73b92c8f8b5b2ddf33077970a23 (patch) | |
| tree | 45bf2097d56215c00b0ca9766e3e878ca4d989c7 /fs/btrfs/super.c | |
| parent | bfceac7fd3c47175fec75c32071051de5969a34c (diff) | |
| download | linux-37f85ec320e6d73b92c8f8b5b2ddf33077970a23.tar.xz | |
btrfs: use named constant for reserved device space
There's a reserved space on each device of size 1MiB that can be used by
bootloaders or to avoid accidental overwrite. Use a symbolic constant
with the explaining comment instead of hard coding the value and
multiple comments.
Note: since btrfs-progs v4.1, mkfs.btrfs will reserve the first 1MiB for
the primary super block (at offset 64KiB), until then the range could
have been used by mistake. Kernel has been always respecting the 1MiB
range for writes.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/super.c')
| -rw-r--r-- | fs/btrfs/super.c | 12 |
1 files changed, 4 insertions, 8 deletions
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 719dda57dc7a..41652dcd16f4 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -2272,17 +2272,13 @@ static inline int btrfs_calc_avail_data_space(struct btrfs_fs_info *fs_info, 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. + * Ensure we have at least min_stripe_size on top of the + * reserved space on the device. */ - if (avail_space <= SZ_1M + min_stripe_size) + if (avail_space <= BTRFS_DEVICE_RANGE_RESERVED + min_stripe_size) continue; - avail_space -= SZ_1M; + avail_space -= BTRFS_DEVICE_RANGE_RESERVED; devices_info[i].dev = device; devices_info[i].max_avail = avail_space; |