diff options
| -rw-r--r-- | fs/xfs/libxfs/xfs_attr_leaf.c | 84 | ||||
| -rw-r--r-- | fs/xfs/libxfs/xfs_da_format.h | 14 |
2 files changed, 92 insertions, 6 deletions
diff --git a/fs/xfs/libxfs/xfs_attr_leaf.c b/fs/xfs/libxfs/xfs_attr_leaf.c index 3337516feeb0..149ef3f66735 100644 --- a/fs/xfs/libxfs/xfs_attr_leaf.c +++ b/fs/xfs/libxfs/xfs_attr_leaf.c @@ -86,6 +86,80 @@ STATIC void xfs_attr3_leaf_moveents(struct xfs_da_args *args, int move_count); STATIC int xfs_attr_leaf_entsize(xfs_attr_leafblock_t *leaf, int index); +/* + * attr3 block 'firstused' conversion helpers. + * + * firstused refers to the offset of the first used byte of the nameval region + * of an attr leaf block. The region starts at the tail of the block and expands + * backwards towards the middle. As such, firstused is initialized to the block + * size for an empty leaf block and is reduced from there. + * + * The attr3 block size is pegged to the fsb size and the maximum fsb is 64k. + * The in-core firstused field is 32-bit and thus supports the maximum fsb size. + * The on-disk field is only 16-bit, however, and overflows at 64k. Since this + * only occurs at exactly 64k, we use zero as a magic on-disk value to represent + * the attr block size. The following helpers manage the conversion between the + * in-core and on-disk formats. + */ + +static void +xfs_attr3_leaf_firstused_from_disk( + struct xfs_da_geometry *geo, + struct xfs_attr3_icleaf_hdr *to, + struct xfs_attr_leafblock *from) +{ + struct xfs_attr3_leaf_hdr *hdr3; + + if (from->hdr.info.magic == cpu_to_be16(XFS_ATTR3_LEAF_MAGIC)) { + hdr3 = (struct xfs_attr3_leaf_hdr *) from; + to->firstused = be16_to_cpu(hdr3->firstused); + } else { + to->firstused = be16_to_cpu(from->hdr.firstused); + } + + /* + * Convert from the magic fsb size value to actual blocksize. This + * should only occur for empty blocks when the block size overflows + * 16-bits. + */ + if (to->firstused == XFS_ATTR3_LEAF_NULLOFF) { + ASSERT(!to->count && !to->usedbytes); + ASSERT(geo->blksize > USHRT_MAX); + to->firstused = geo->blksize; + } +} + +static void +xfs_attr3_leaf_firstused_to_disk( + struct xfs_da_geometry *geo, + struct xfs_attr_leafblock *to, + struct xfs_attr3_icleaf_hdr *from) +{ + struct xfs_attr3_leaf_hdr *hdr3; + uint32_t firstused; + + /* magic value should only be seen on disk */ + ASSERT(from->firstused != XFS_ATTR3_LEAF_NULLOFF); + + /* + * Scale down the 32-bit in-core firstused value to the 16-bit on-disk + * value. This only overflows at the max supported value of 64k. Use the + * magic on-disk value to represent block size in this case. + */ + firstused = from->firstused; + if (firstused > USHRT_MAX) { + ASSERT(from->firstused == geo->blksize); + firstused = XFS_ATTR3_LEAF_NULLOFF; + } + + if (from->magic == XFS_ATTR3_LEAF_MAGIC) { + hdr3 = (struct xfs_attr3_leaf_hdr *) to; + hdr3->firstused = cpu_to_be16(firstused); + } else { + to->hdr.firstused = cpu_to_be16(firstused); + } +} + void xfs_attr3_leaf_hdr_from_disk( struct xfs_da_geometry *geo, @@ -105,7 +179,7 @@ xfs_attr3_leaf_hdr_from_disk( to->magic = be16_to_cpu(hdr3->info.hdr.magic); to->count = be16_to_cpu(hdr3->count); to->usedbytes = be16_to_cpu(hdr3->usedbytes); - to->firstused = be16_to_cpu(hdr3->firstused); + xfs_attr3_leaf_firstused_from_disk(geo, to, from); to->holes = hdr3->holes; for (i = 0; i < XFS_ATTR_LEAF_MAPSIZE; i++) { @@ -119,7 +193,7 @@ xfs_attr3_leaf_hdr_from_disk( to->magic = be16_to_cpu(from->hdr.info.magic); to->count = be16_to_cpu(from->hdr.count); to->usedbytes = be16_to_cpu(from->hdr.usedbytes); - to->firstused = be16_to_cpu(from->hdr.firstused); + xfs_attr3_leaf_firstused_from_disk(geo, to, from); to->holes = from->hdr.holes; for (i = 0; i < XFS_ATTR_LEAF_MAPSIZE; i++) { @@ -134,7 +208,7 @@ xfs_attr3_leaf_hdr_to_disk( struct xfs_attr_leafblock *to, struct xfs_attr3_icleaf_hdr *from) { - int i; + int i; ASSERT(from->magic == XFS_ATTR_LEAF_MAGIC || from->magic == XFS_ATTR3_LEAF_MAGIC); @@ -147,7 +221,7 @@ xfs_attr3_leaf_hdr_to_disk( hdr3->info.hdr.magic = cpu_to_be16(from->magic); hdr3->count = cpu_to_be16(from->count); hdr3->usedbytes = cpu_to_be16(from->usedbytes); - hdr3->firstused = cpu_to_be16(from->firstused); + xfs_attr3_leaf_firstused_to_disk(geo, to, from); hdr3->holes = from->holes; hdr3->pad1 = 0; @@ -162,7 +236,7 @@ xfs_attr3_leaf_hdr_to_disk( to->hdr.info.magic = cpu_to_be16(from->magic); to->hdr.count = cpu_to_be16(from->count); to->hdr.usedbytes = cpu_to_be16(from->usedbytes); - to->hdr.firstused = cpu_to_be16(from->firstused); + xfs_attr3_leaf_firstused_to_disk(geo, to, from); to->hdr.holes = from->holes; to->hdr.pad1 = 0; diff --git a/fs/xfs/libxfs/xfs_da_format.h b/fs/xfs/libxfs/xfs_da_format.h index 0a49b0286372..74bcbabfa523 100644 --- a/fs/xfs/libxfs/xfs_da_format.h +++ b/fs/xfs/libxfs/xfs_da_format.h @@ -725,7 +725,13 @@ struct xfs_attr3_icleaf_hdr { __uint16_t magic; __uint16_t count; __uint16_t usedbytes; - __uint16_t firstused; + /* + * firstused is 32-bit here instead of 16-bit like the on-disk variant + * to support maximum fsb size of 64k without overflow issues throughout + * the attr code. Instead, the overflow condition is handled on + * conversion to/from disk. + */ + __uint32_t firstused; __u8 holes; struct { __uint16_t base; @@ -734,6 +740,12 @@ struct xfs_attr3_icleaf_hdr { }; /* + * Special value to represent fs block size in the leaf header firstused field. + * Only used when block size overflows the 2-bytes available on disk. + */ +#define XFS_ATTR3_LEAF_NULLOFF 0 + +/* * Flags used in the leaf_entry[i].flags field. * NOTE: the INCOMPLETE bit must not collide with the flags bits specified * on the system call, they are "or"ed together for various operations. |
