diff options
Diffstat (limited to 'fs/xfs/xfs_attr_leaf.h')
-rw-r--r-- | fs/xfs/xfs_attr_leaf.h | 232 |
1 files changed, 232 insertions, 0 deletions
diff --git a/fs/xfs/xfs_attr_leaf.h b/fs/xfs/xfs_attr_leaf.h index 3ec5ec0..c102213 100644 --- a/fs/xfs/xfs_attr_leaf.h +++ b/fs/xfs/xfs_attr_leaf.h @@ -19,6 +19,16 @@ #ifndef __XFS_ATTR_LEAF_H__ #define __XFS_ATTR_LEAF_H__ +/* + * Attribute storage layout, internal structure, access macros, etc. + * + * Attribute lists are structured around Btrees where all the data + * elements are in the leaf nodes. Attribute names are hashed into an int, + * then that int is used as the index into the Btree. Since the hashval + * of an attribute name may not be unique, we may have duplicate keys. The + * internal links in the Btree are logical block offsets into the file. + */ + struct attrlist; struct attrlist_cursor_kern; struct xfs_attr_list_context; @@ -28,6 +38,226 @@ struct xfs_da_state_blk; struct xfs_inode; struct xfs_trans; +/*======================================================================== + * Attribute structure when equal to XFS_LBSIZE(mp) bytes. + *========================================================================*/ + +/* + * This is the structure of the leaf nodes in the Btree. + * + * Struct leaf_entry's are packed from the top. Name/values grow from the + * bottom but are not packed. The freemap contains run-length-encoded entries + * for the free bytes after the leaf_entry's, but only the N largest such, + * smaller runs are dropped. When the freemap doesn't show enough space + * for an allocation, we compact the name/value area and try again. If we + * still don't have enough space, then we have to split the block. The + * name/value structs (both local and remote versions) must be 32bit aligned. + * + * Since we have duplicate hash keys, for each key that matches, compare + * the actual name string. The root and intermediate node search always + * takes the first-in-the-block key match found, so we should only have + * to work "forw"ard. If none matches, continue with the "forw"ard leaf + * nodes until the hash key changes or the attribute name is found. + * + * We store the fact that an attribute is a ROOT/USER/SECURE attribute in + * the leaf_entry. The namespaces are independent only because we also look + * at the namespace bit when we are looking for a matching attribute name. + * + * We also store an "incomplete" bit in the leaf_entry. It shows that an + * attribute is in the middle of being created and should not be shown to + * the user if we crash during the time that the bit is set. We clear the + * bit when we have finished setting up the attribute. We do this because + * we cannot create some large attributes inside a single transaction, and we + * need some indication that we weren't finished if we crash in the middle. + */ +#define XFS_ATTR_LEAF_MAPSIZE 3 /* how many freespace slots */ + +typedef struct xfs_attr_leaf_map { /* RLE map of free bytes */ + __be16 base; /* base of free region */ + __be16 size; /* length of free region */ +} xfs_attr_leaf_map_t; + +typedef struct xfs_attr_leaf_hdr { /* constant-structure header block */ + xfs_da_blkinfo_t info; /* block type, links, etc. */ + __be16 count; /* count of active leaf_entry's */ + __be16 usedbytes; /* num bytes of names/values stored */ + __be16 firstused; /* first used byte in name area */ + __u8 holes; /* != 0 if blk needs compaction */ + __u8 pad1; + xfs_attr_leaf_map_t freemap[XFS_ATTR_LEAF_MAPSIZE]; + /* N largest free regions */ +} xfs_attr_leaf_hdr_t; + +typedef struct xfs_attr_leaf_entry { /* sorted on key, not name */ + __be32 hashval; /* hash value of name */ + __be16 nameidx; /* index into buffer of name/value */ + __u8 flags; /* LOCAL/ROOT/SECURE/INCOMPLETE flag */ + __u8 pad2; /* unused pad byte */ +} xfs_attr_leaf_entry_t; + +typedef struct xfs_attr_leaf_name_local { + __be16 valuelen; /* number of bytes in value */ + __u8 namelen; /* length of name bytes */ + __u8 nameval[1]; /* name/value bytes */ +} xfs_attr_leaf_name_local_t; + +typedef struct xfs_attr_leaf_name_remote { + __be32 valueblk; /* block number of value bytes */ + __be32 valuelen; /* number of bytes in value */ + __u8 namelen; /* length of name bytes */ + __u8 name[1]; /* name bytes */ +} xfs_attr_leaf_name_remote_t; + +typedef struct xfs_attr_leafblock { + xfs_attr_leaf_hdr_t hdr; /* constant-structure header block */ + xfs_attr_leaf_entry_t entries[1]; /* sorted on key, not name */ + xfs_attr_leaf_name_local_t namelist; /* grows from bottom of buf */ + xfs_attr_leaf_name_remote_t valuelist; /* grows from bottom of buf */ +} xfs_attr_leafblock_t; + +/* + * CRC enabled leaf structures. Called "version 3" structures to match the + * version number of the directory and dablk structures for this feature, and + * attr2 is already taken by the variable inode attribute fork size feature. + */ +struct xfs_attr3_leaf_hdr { + struct xfs_da3_blkinfo info; + __be16 count; + __be16 usedbytes; + __be16 firstused; + __u8 holes; + __u8 pad1; + struct xfs_attr_leaf_map freemap[XFS_ATTR_LEAF_MAPSIZE]; + __be32 pad2; /* 64 bit alignment */ +}; + +#define XFS_ATTR3_LEAF_CRC_OFF (offsetof(struct xfs_attr3_leaf_hdr, info.crc)) + +struct xfs_attr3_leafblock { + struct xfs_attr3_leaf_hdr hdr; + struct xfs_attr_leaf_entry entries[1]; + + /* + * The rest of the block contains the following structures after the + * leaf entries, growing from the bottom up. The variables are never + * referenced, the locations accessed purely from helper functions. + * + * struct xfs_attr_leaf_name_local + * struct xfs_attr_leaf_name_remote + */ +}; + +/* + * incore, neutral version of the attribute leaf header + */ +struct xfs_attr3_icleaf_hdr { + __uint32_t forw; + __uint32_t back; + __uint16_t magic; + __uint16_t count; + __uint16_t usedbytes; + __uint16_t firstused; + __u8 holes; + struct { + __uint16_t base; + __uint16_t size; + } freemap[XFS_ATTR_LEAF_MAPSIZE]; +}; + +/* + * 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. + */ +#define XFS_ATTR_LOCAL_BIT 0 /* attr is stored locally */ +#define XFS_ATTR_ROOT_BIT 1 /* limit access to trusted attrs */ +#define XFS_ATTR_SECURE_BIT 2 /* limit access to secure attrs */ +#define XFS_ATTR_INCOMPLETE_BIT 7 /* attr in middle of create/delete */ +#define XFS_ATTR_LOCAL (1 << XFS_ATTR_LOCAL_BIT) +#define XFS_ATTR_ROOT (1 << XFS_ATTR_ROOT_BIT) +#define XFS_ATTR_SECURE (1 << XFS_ATTR_SECURE_BIT) +#define XFS_ATTR_INCOMPLETE (1 << XFS_ATTR_INCOMPLETE_BIT) + +/* + * Conversion macros for converting namespace bits from argument flags + * to ondisk flags. + */ +#define XFS_ATTR_NSP_ARGS_MASK (ATTR_ROOT | ATTR_SECURE) +#define XFS_ATTR_NSP_ONDISK_MASK (XFS_ATTR_ROOT | XFS_ATTR_SECURE) +#define XFS_ATTR_NSP_ONDISK(flags) ((flags) & XFS_ATTR_NSP_ONDISK_MASK) +#define XFS_ATTR_NSP_ARGS(flags) ((flags) & XFS_ATTR_NSP_ARGS_MASK) +#define XFS_ATTR_NSP_ARGS_TO_ONDISK(x) (((x) & ATTR_ROOT ? XFS_ATTR_ROOT : 0) |\ + ((x) & ATTR_SECURE ? XFS_ATTR_SECURE : 0)) +#define XFS_ATTR_NSP_ONDISK_TO_ARGS(x) (((x) & XFS_ATTR_ROOT ? ATTR_ROOT : 0) |\ + ((x) & XFS_ATTR_SECURE ? ATTR_SECURE : 0)) + +/* + * Alignment for namelist and valuelist entries (since they are mixed + * there can be only one alignment value) + */ +#define XFS_ATTR_LEAF_NAME_ALIGN ((uint)sizeof(xfs_dablk_t)) + +static inline int +xfs_attr3_leaf_hdr_size(struct xfs_attr_leafblock *leafp) +{ + if (leafp->hdr.info.magic == cpu_to_be16(XFS_ATTR3_LEAF_MAGIC)) + return sizeof(struct xfs_attr3_leaf_hdr); + return sizeof(struct xfs_attr_leaf_hdr); +} + +static inline struct xfs_attr_leaf_entry * +xfs_attr3_leaf_entryp(xfs_attr_leafblock_t *leafp) +{ + if (leafp->hdr.info.magic == cpu_to_be16(XFS_ATTR3_LEAF_MAGIC)) + return &((struct xfs_attr3_leafblock *)leafp)->entries[0]; + return &leafp->entries[0]; +} + +/* + * Cast typed pointers for "local" and "remote" name/value structs. + */ +static inline char * +xfs_attr3_leaf_name(xfs_attr_leafblock_t *leafp, int idx) +{ + struct xfs_attr_leaf_entry *entries = xfs_attr3_leaf_entryp(leafp); + + return &((char *)leafp)[be16_to_cpu(entries[idx].nameidx)]; +} + +static inline xfs_attr_leaf_name_remote_t * +xfs_attr3_leaf_name_remote(xfs_attr_leafblock_t *leafp, int idx) +{ + return (xfs_attr_leaf_name_remote_t *)xfs_attr3_leaf_name(leafp, idx); +} + +static inline xfs_attr_leaf_name_local_t * +xfs_attr3_leaf_name_local(xfs_attr_leafblock_t *leafp, int idx) +{ + return (xfs_attr_leaf_name_local_t *)xfs_attr3_leaf_name(leafp, idx); +} + +/* + * Calculate total bytes used (including trailing pad for alignment) for + * a "local" name/value structure, a "remote" name/value structure, and + * a pointer which might be either. + */ +static inline int xfs_attr_leaf_entsize_remote(int nlen) +{ + return ((uint)sizeof(xfs_attr_leaf_name_remote_t) - 1 + (nlen) + \ + XFS_ATTR_LEAF_NAME_ALIGN - 1) & ~(XFS_ATTR_LEAF_NAME_ALIGN - 1); +} + +static inline int xfs_attr_leaf_entsize_local(int nlen, int vlen) +{ + return ((uint)sizeof(xfs_attr_leaf_name_local_t) - 1 + (nlen) + (vlen) + + XFS_ATTR_LEAF_NAME_ALIGN - 1) & ~(XFS_ATTR_LEAF_NAME_ALIGN - 1); +} + +static inline int xfs_attr_leaf_entsize_local_max(int bsize) +{ + return (((bsize) >> 1) + ((bsize) >> 2)); +} + /* * Used to keep a list of "remote value" extents when unlinking an inode. */ @@ -106,4 +336,6 @@ void xfs_attr3_leaf_hdr_from_disk(struct xfs_attr3_icleaf_hdr *to, void xfs_attr3_leaf_hdr_to_disk(struct xfs_attr_leafblock *to, struct xfs_attr3_icleaf_hdr *from); +extern const struct xfs_buf_ops xfs_attr3_leaf_buf_ops; + #endif /* __XFS_ATTR_LEAF_H__ */ |