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btrfs: free-space-cache: use unaligned helpers to access data

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The free space inode stores the tracking data, checksums etc, using the
io_ctl structure and moving the pointers. The data are generally aligned
to at least 4 bytes (u32 for CRC) so it's not completely unaligned but
for clarity we should use the proper helpers whenever a struct is
initialized from io_ctl->cur pointer.

Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
David Sterba 2020-09-15 13:32:34 +02:00
parent e2f896b318
commit 6994ca367c
1 changed files with 9 additions and 12 deletions
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21
fs/btrfs/free-space-cache.c
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@ -413,8 +413,6 @@ static int io_ctl_prepare_pages(struct btrfs_io_ctl *io_ctl, bool uptodate)
static void io_ctl_set_generation(struct btrfs_io_ctl *io_ctl, u64 generation)
{
__le64 *val;
io_ctl_map_page(io_ctl, 1);
/*
@ -429,14 +427,13 @@ static void io_ctl_set_generation(struct btrfs_io_ctl *io_ctl, u64 generation)
io_ctl->size -= sizeof(u64) * 2;
}
val = io_ctl->cur;
*val = cpu_to_le64(generation);
put_unaligned_le64(generation, io_ctl->cur);
io_ctl->cur += sizeof(u64);
}
static int io_ctl_check_generation(struct btrfs_io_ctl *io_ctl, u64 generation)
{
__le64 *gen;
u64 cache_gen;
/*
* Skip the crc area. If we don't check crcs then we just have a 64bit
@ -451,11 +448,11 @@ static int io_ctl_check_generation(struct btrfs_io_ctl *io_ctl, u64 generation)
io_ctl->size -= sizeof(u64) * 2;
}
gen = io_ctl->cur;
if (le64_to_cpu(*gen) != generation) {
cache_gen = get_unaligned_le64(io_ctl->cur);
if (cache_gen != generation) {
btrfs_err_rl(io_ctl->fs_info,
"space cache generation (%llu) does not match inode (%llu)",
*gen, generation);
cache_gen, generation);
io_ctl_unmap_page(io_ctl);
return -EIO;
}
@ -525,8 +522,8 @@ static int io_ctl_add_entry(struct btrfs_io_ctl *io_ctl, u64 offset, u64 bytes,
return -ENOSPC;
entry = io_ctl->cur;
entry->offset = cpu_to_le64(offset);
entry->bytes = cpu_to_le64(bytes);
put_unaligned_le64(offset, &entry->offset);
put_unaligned_le64(bytes, &entry->bytes);
entry->type = (bitmap) ? BTRFS_FREE_SPACE_BITMAP :
BTRFS_FREE_SPACE_EXTENT;
io_ctl->cur += sizeof(struct btrfs_free_space_entry);
@ -599,8 +596,8 @@ static int io_ctl_read_entry(struct btrfs_io_ctl *io_ctl,
}
e = io_ctl->cur;
entry->offset = le64_to_cpu(e->offset);
entry->bytes = le64_to_cpu(e->bytes);
entry->offset = get_unaligned_le64(&e->offset);
entry->bytes = get_unaligned_le64(&e->bytes);
*type = e->type;
io_ctl->cur += sizeof(struct btrfs_free_space_entry);
io_ctl->size -= sizeof(struct btrfs_free_space_entry);