diff options
Diffstat (limited to '')
| -rw-r--r-- | fs/xfs/libxfs/xfs_log_format.h | 19 |
1 files changed, 14 insertions, 5 deletions
diff --git a/fs/xfs/libxfs/xfs_log_format.h b/fs/xfs/libxfs/xfs_log_format.h index 8ef31d71a9c7..9bac0d2e56dc 100644 --- a/fs/xfs/libxfs/xfs_log_format.h +++ b/fs/xfs/libxfs/xfs_log_format.h @@ -462,11 +462,20 @@ static inline uint xfs_log_dinode_size(int version) #define XFS_BLF_GDQUOT_BUF (1<<4) /* - * This is the structure used to lay out a buf log item in the - * log. The data map describes which 128 byte chunks of the buffer - * have been logged. - */ -#define XFS_BLF_DATAMAP_SIZE ((XFS_MAX_BLOCKSIZE / XFS_BLF_CHUNK) / NBWORD) + * This is the structure used to lay out a buf log item in the log. The data + * map describes which 128 byte chunks of the buffer have been logged. + * + * The placement of blf_map_size causes blf_data_map to start at an odd + * multiple of sizeof(unsigned int) offset within the struct. Because the data + * bitmap size will always be an even number, the end of the data_map (and + * therefore the structure) will also be at an odd multiple of sizeof(unsigned + * int). Some 64-bit compilers will insert padding at the end of the struct to + * ensure 64-bit alignment of blf_blkno, but 32-bit ones will not. Therefore, + * XFS_BLF_DATAMAP_SIZE must be an odd number to make the padding explicit and + * keep the structure size consistent between 32-bit and 64-bit platforms. + */ +#define __XFS_BLF_DATAMAP_SIZE ((XFS_MAX_BLOCKSIZE / XFS_BLF_CHUNK) / NBWORD) +#define XFS_BLF_DATAMAP_SIZE (__XFS_BLF_DATAMAP_SIZE + 1) typedef struct xfs_buf_log_format { unsigned short blf_type; /* buf log item type indicator */ |