super.magic is an le64 but it''s treated as an unterminated string when
compared against BTRFS_MAGIC which is defined as a string. Instead
define BTRFS_MAGIC as a normal hex value and use endian helpers to
compare it to the super''s magic.
I tested this by mounting an fs made before the change and made sure
that it didn''t introduce sparse errors. This matches a similar cleanup
that is pending in btrfs-progs. David Sterba pointed out that we should
fix the kernel side as well :).
Signed-off-by: Zach Brown <zab@redhat.com>
---
fs/btrfs/check-integrity.c | 3 +--
fs/btrfs/ctree.h | 2 +-
fs/btrfs/disk-io.c | 6 ++----
fs/btrfs/volumes.c | 3 +--
4 files changed, 5 insertions(+), 9 deletions(-)
diff --git a/fs/btrfs/check-integrity.c b/fs/btrfs/check-integrity.c
index 11d47bf..18af6f4 100644
--- a/fs/btrfs/check-integrity.c
+++ b/fs/btrfs/check-integrity.c
@@ -813,8 +813,7 @@ static int btrfsic_process_superblock_dev_mirror(
(bh->b_data + (dev_bytenr & 4095));
if (btrfs_super_bytenr(super_tmp) != dev_bytenr ||
- strncmp((char *)(&(super_tmp->magic)), BTRFS_MAGIC,
- sizeof(super_tmp->magic)) ||
+ super_tmp->magic != cpu_to_le64(BTRFS_MAGIC) ||
memcmp(device->uuid, super_tmp->dev_item.uuid, BTRFS_UUID_SIZE) ||
btrfs_super_nodesize(super_tmp) != state->metablock_size ||
btrfs_super_leafsize(super_tmp) != state->metablock_size ||
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 9f72ec8..8d88d1e 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -46,7 +46,7 @@ extern struct kmem_cache *btrfs_path_cachep;
extern struct kmem_cache *btrfs_free_space_cachep;
struct btrfs_ordered_sum;
-#define BTRFS_MAGIC "_BHRfS_M"
+#define BTRFS_MAGIC 0x4D5F53665248425FULL /* ascii _BHRfS_M, no null */
#define BTRFS_MAX_MIRRORS 3
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 6baa77d..1d1ba22 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2407,8 +2407,7 @@ int open_ctree(struct super_block *sb,
sb->s_blocksize = sectorsize;
sb->s_blocksize_bits = blksize_bits(sectorsize);
- if (strncmp((char *)(&disk_super->magic), BTRFS_MAGIC,
- sizeof(disk_super->magic))) {
+ if (disk_super->magic != cpu_to_le64(BTRFS_MAGIC)) {
printk(KERN_INFO "btrfs: valid FS not found on %s\n", sb->s_id);
goto fail_sb_buffer;
}
@@ -2815,8 +2814,7 @@ struct buffer_head *btrfs_read_dev_super(struct
block_device *bdev)
super = (struct btrfs_super_block *)bh->b_data;
if (btrfs_super_bytenr(super) != bytenr ||
- strncmp((char *)(&super->magic), BTRFS_MAGIC,
- sizeof(super->magic))) {
+ super->magic != cpu_to_le64(BTRFS_MAGIC)) {
brelse(bh);
continue;
}
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 5670765..72b1cf1 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -855,8 +855,7 @@ int btrfs_scan_one_device(const char *path, fmode_t flags,
void *holder,
disk_super = p + (bytenr & ~PAGE_CACHE_MASK);
if (btrfs_super_bytenr(disk_super) != bytenr ||
- strncmp((char *)(&disk_super->magic), BTRFS_MAGIC,
- sizeof(disk_super->magic)))
+ disk_super->magic != cpu_to_le64(BTRFS_MAGIC))
goto error_unmap;
devid = btrfs_stack_device_id(&disk_super->dev_item);
--
1.7.11.7
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