1 /*
2 * Copyright (c) 2000,2002-2003,2005 Silicon Graphics, Inc.
3 * All Rights Reserved.
4 *
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License as
7 * published by the Free Software Foundation.
8 *
9 * This program is distributed in the hope that it would be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
17 */
18 #ifndef __XFS_ATTR_LEAF_H__
19 #define __XFS_ATTR_LEAF_H__
20
21 /*
22 * Attribute storage layout, internal structure, access macros, etc.
23 *
24 * Attribute lists are structured around Btrees where all the data
25 * elements are in the leaf nodes. Attribute names are hashed into an int,
26 * then that int is used as the index into the Btree. Since the hashval
27 * of an attribute name may not be unique, we may have duplicate keys. The
28 * internal links in the Btree are logical block offsets into the file.
29 */
30
31 struct attrlist;
32 struct attrlist_cursor_kern;
33 struct xfs_attr_list_context;
34 struct xfs_dabuf;
35 struct xfs_da_args;
36 struct xfs_da_state;
37 struct xfs_da_state_blk;
38 struct xfs_inode;
39 struct xfs_trans;
40
41 /*========================================================================
42 * Attribute structure when equal to XFS_LBSIZE(mp) bytes.
43 *========================================================================*/
44
45 /*
46 * This is the structure of the leaf nodes in the Btree.
47 *
48 * Struct leaf_entry's are packed from the top. Name/values grow from the
49 * bottom but are not packed. The freemap contains run-length-encoded entries
50 * for the free bytes after the leaf_entry's, but only the N largest such,
51 * smaller runs are dropped. When the freemap doesn't show enough space
52 * for an allocation, we compact the name/value area and try again. If we
53 * still don't have enough space, then we have to split the block. The
54 * name/value structs (both local and remote versions) must be 32bit aligned.
55 *
56 * Since we have duplicate hash keys, for each key that matches, compare
57 * the actual name string. The root and intermediate node search always
58 * takes the first-in-the-block key match found, so we should only have
59 * to work "forw"ard. If none matches, continue with the "forw"ard leaf
60 * nodes until the hash key changes or the attribute name is found.
61 *
62 * We store the fact that an attribute is a ROOT/USER/SECURE attribute in
63 * the leaf_entry. The namespaces are independent only because we also look
64 * at the namespace bit when we are looking for a matching attribute name.
65 *
66 * We also store an "incomplete" bit in the leaf_entry. It shows that an
67 * attribute is in the middle of being created and should not be shown to
68 * the user if we crash during the time that the bit is set. We clear the
69 * bit when we have finished setting up the attribute. We do this because
70 * we cannot create some large attributes inside a single transaction, and we
71 * need some indication that we weren't finished if we crash in the middle.
72 */
73 #define XFS_ATTR_LEAF_MAPSIZE 3 /* how many freespace slots */
74
75 typedef struct xfs_attr_leaf_map { /* RLE map of free bytes */
76 __be16 base; /* base of free region */
77 __be16 size; /* length of free region */
78 } xfs_attr_leaf_map_t;
79
80 typedef struct xfs_attr_leaf_hdr { /* constant-structure header block */
81 xfs_da_blkinfo_t info; /* block type, links, etc. */
82 __be16 count; /* count of active leaf_entry's */
83 __be16 usedbytes; /* num bytes of names/values stored */
84 __be16 firstused; /* first used byte in name area */
85 __u8 holes; /* != 0 if blk needs compaction */
86 __u8 pad1;
87 xfs_attr_leaf_map_t freemap[XFS_ATTR_LEAF_MAPSIZE];
88 /* N largest free regions */
89 } xfs_attr_leaf_hdr_t;
90
91 typedef struct xfs_attr_leaf_entry { /* sorted on key, not name */
92 __be32 hashval; /* hash value of name */
93 __be16 nameidx; /* index into buffer of name/value */
94 __u8 flags; /* LOCAL/ROOT/SECURE/INCOMPLETE flag */
95 __u8 pad2; /* unused pad byte */
96 } xfs_attr_leaf_entry_t;
97
98 typedef struct xfs_attr_leaf_name_local {
99 __be16 valuelen; /* number of bytes in value */
100 __u8 namelen; /* length of name bytes */
101 __u8 nameval[1]; /* name/value bytes */
102 } xfs_attr_leaf_name_local_t;
103
104 typedef struct xfs_attr_leaf_name_remote {
105 __be32 valueblk; /* block number of value bytes */
106 __be32 valuelen; /* number of bytes in value */
107 __u8 namelen; /* length of name bytes */
108 __u8 name[1]; /* name bytes */
109 } xfs_attr_leaf_name_remote_t;
110
111 typedef struct xfs_attr_leafblock {
112 xfs_attr_leaf_hdr_t hdr; /* constant-structure header block */
113 xfs_attr_leaf_entry_t entries[1]; /* sorted on key, not name */
114 xfs_attr_leaf_name_local_t namelist; /* grows from bottom of buf */
115 xfs_attr_leaf_name_remote_t valuelist; /* grows from bottom of buf */
116 } xfs_attr_leafblock_t;
117
118 /*
119 * Flags used in the leaf_entry[i].flags field.
120 * NOTE: the INCOMPLETE bit must not collide with the flags bits specified
121 * on the system call, they are "or"ed together for various operations.
122 */
123 #define XFS_ATTR_LOCAL_BIT 0 /* attr is stored locally */
124 #define XFS_ATTR_ROOT_BIT 1 /* limit access to trusted attrs */
125 #define XFS_ATTR_SECURE_BIT 2 /* limit access to secure attrs */
126 #define XFS_ATTR_INCOMPLETE_BIT 7 /* attr in middle of create/delete */
127 #define XFS_ATTR_LOCAL (1 << XFS_ATTR_LOCAL_BIT)
128 #define XFS_ATTR_ROOT (1 << XFS_ATTR_ROOT_BIT)
129 #define XFS_ATTR_SECURE (1 << XFS_ATTR_SECURE_BIT)
130 #define XFS_ATTR_INCOMPLETE (1 << XFS_ATTR_INCOMPLETE_BIT)
131
132 /*
133 * Conversion macros for converting namespace bits from argument flags
134 * to ondisk flags.
135 */
136 #define XFS_ATTR_NSP_ARGS_MASK (ATTR_ROOT | ATTR_SECURE)
137 #define XFS_ATTR_NSP_ONDISK_MASK (XFS_ATTR_ROOT | XFS_ATTR_SECURE)
138 #define XFS_ATTR_NSP_ONDISK(flags) ((flags) & XFS_ATTR_NSP_ONDISK_MASK)
139 #define XFS_ATTR_NSP_ARGS(flags) ((flags) & XFS_ATTR_NSP_ARGS_MASK)
140 #define XFS_ATTR_NSP_ARGS_TO_ONDISK(x) (((x) & ATTR_ROOT ? XFS_ATTR_ROOT : 0) |\
141 ((x) & ATTR_SECURE ? XFS_ATTR_SECURE : 0))
142 #define XFS_ATTR_NSP_ONDISK_TO_ARGS(x) (((x) & XFS_ATTR_ROOT ? ATTR_ROOT : 0) |\
143 ((x) & XFS_ATTR_SECURE ? ATTR_SECURE : 0))
144
145 /*
146 * Alignment for namelist and valuelist entries (since they are mixed
147 * there can be only one alignment value)
148 */
149 #define XFS_ATTR_LEAF_NAME_ALIGN ((uint)sizeof(xfs_dablk_t))
150
151 /*
152 * Cast typed pointers for "local" and "remote" name/value structs.
153 */
154 static inline xfs_attr_leaf_name_remote_t *
xfs_attr_leaf_name_remote(xfs_attr_leafblock_t * leafp,int idx)155 xfs_attr_leaf_name_remote(xfs_attr_leafblock_t *leafp, int idx)
156 {
157 return (xfs_attr_leaf_name_remote_t *)
158 &((char *)leafp)[be16_to_cpu(leafp->entries[idx].nameidx)];
159 }
160
161 static inline xfs_attr_leaf_name_local_t *
xfs_attr_leaf_name_local(xfs_attr_leafblock_t * leafp,int idx)162 xfs_attr_leaf_name_local(xfs_attr_leafblock_t *leafp, int idx)
163 {
164 return (xfs_attr_leaf_name_local_t *)
165 &((char *)leafp)[be16_to_cpu(leafp->entries[idx].nameidx)];
166 }
167
xfs_attr_leaf_name(xfs_attr_leafblock_t * leafp,int idx)168 static inline char *xfs_attr_leaf_name(xfs_attr_leafblock_t *leafp, int idx)
169 {
170 return &((char *)leafp)[be16_to_cpu(leafp->entries[idx].nameidx)];
171 }
172
173 /*
174 * Calculate total bytes used (including trailing pad for alignment) for
175 * a "local" name/value structure, a "remote" name/value structure, and
176 * a pointer which might be either.
177 */
xfs_attr_leaf_entsize_remote(int nlen)178 static inline int xfs_attr_leaf_entsize_remote(int nlen)
179 {
180 return ((uint)sizeof(xfs_attr_leaf_name_remote_t) - 1 + (nlen) + \
181 XFS_ATTR_LEAF_NAME_ALIGN - 1) & ~(XFS_ATTR_LEAF_NAME_ALIGN - 1);
182 }
183
xfs_attr_leaf_entsize_local(int nlen,int vlen)184 static inline int xfs_attr_leaf_entsize_local(int nlen, int vlen)
185 {
186 return ((uint)sizeof(xfs_attr_leaf_name_local_t) - 1 + (nlen) + (vlen) +
187 XFS_ATTR_LEAF_NAME_ALIGN - 1) & ~(XFS_ATTR_LEAF_NAME_ALIGN - 1);
188 }
189
xfs_attr_leaf_entsize_local_max(int bsize)190 static inline int xfs_attr_leaf_entsize_local_max(int bsize)
191 {
192 return (((bsize) >> 1) + ((bsize) >> 2));
193 }
194
195 /*
196 * Used to keep a list of "remote value" extents when unlinking an inode.
197 */
198 typedef struct xfs_attr_inactive_list {
199 xfs_dablk_t valueblk; /* block number of value bytes */
200 int valuelen; /* number of bytes in value */
201 } xfs_attr_inactive_list_t;
202
203
204 /*========================================================================
205 * Function prototypes for the kernel.
206 *========================================================================*/
207
208 /*
209 * Internal routines when attribute fork size < XFS_LITINO(mp).
210 */
211 void xfs_attr_shortform_create(struct xfs_da_args *args);
212 void xfs_attr_shortform_add(struct xfs_da_args *args, int forkoff);
213 int xfs_attr_shortform_lookup(struct xfs_da_args *args);
214 int xfs_attr_shortform_getvalue(struct xfs_da_args *args);
215 int xfs_attr_shortform_to_leaf(struct xfs_da_args *args);
216 int xfs_attr_shortform_remove(struct xfs_da_args *args);
217 int xfs_attr_shortform_list(struct xfs_attr_list_context *context);
218 int xfs_attr_shortform_allfit(struct xfs_dabuf *bp, struct xfs_inode *dp);
219 int xfs_attr_shortform_bytesfit(xfs_inode_t *dp, int bytes);
220
221
222 /*
223 * Internal routines when attribute fork size == XFS_LBSIZE(mp).
224 */
225 int xfs_attr_leaf_to_node(struct xfs_da_args *args);
226 int xfs_attr_leaf_to_shortform(struct xfs_dabuf *bp,
227 struct xfs_da_args *args, int forkoff);
228 int xfs_attr_leaf_clearflag(struct xfs_da_args *args);
229 int xfs_attr_leaf_setflag(struct xfs_da_args *args);
230 int xfs_attr_leaf_flipflags(xfs_da_args_t *args);
231
232 /*
233 * Routines used for growing the Btree.
234 */
235 int xfs_attr_leaf_split(struct xfs_da_state *state,
236 struct xfs_da_state_blk *oldblk,
237 struct xfs_da_state_blk *newblk);
238 int xfs_attr_leaf_lookup_int(struct xfs_dabuf *leaf,
239 struct xfs_da_args *args);
240 int xfs_attr_leaf_getvalue(struct xfs_dabuf *bp, struct xfs_da_args *args);
241 int xfs_attr_leaf_add(struct xfs_dabuf *leaf_buffer,
242 struct xfs_da_args *args);
243 int xfs_attr_leaf_remove(struct xfs_dabuf *leaf_buffer,
244 struct xfs_da_args *args);
245 int xfs_attr_leaf_list_int(struct xfs_dabuf *bp,
246 struct xfs_attr_list_context *context);
247
248 /*
249 * Routines used for shrinking the Btree.
250 */
251 int xfs_attr_leaf_toosmall(struct xfs_da_state *state, int *retval);
252 void xfs_attr_leaf_unbalance(struct xfs_da_state *state,
253 struct xfs_da_state_blk *drop_blk,
254 struct xfs_da_state_blk *save_blk);
255 int xfs_attr_root_inactive(struct xfs_trans **trans, struct xfs_inode *dp);
256
257 /*
258 * Utility routines.
259 */
260 xfs_dahash_t xfs_attr_leaf_lasthash(struct xfs_dabuf *bp, int *count);
261 int xfs_attr_leaf_order(struct xfs_dabuf *leaf1_bp,
262 struct xfs_dabuf *leaf2_bp);
263 int xfs_attr_leaf_newentsize(int namelen, int valuelen, int blocksize,
264 int *local);
265 #endif /* __XFS_ATTR_LEAF_H__ */
266