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Commit | Line | Data |
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1da177e4 LT |
1 | Changes since 2.5.0: |
2 | ||
3 | --- | |
4 | [recommended] | |
5 | ||
6 | New helpers: sb_bread(), sb_getblk(), sb_find_get_block(), set_bh(), | |
7 | sb_set_blocksize() and sb_min_blocksize(). | |
8 | ||
9 | Use them. | |
10 | ||
11 | (sb_find_get_block() replaces 2.4's get_hash_table()) | |
12 | ||
13 | --- | |
14 | [recommended] | |
15 | ||
16 | New methods: ->alloc_inode() and ->destroy_inode(). | |
17 | ||
18 | Remove inode->u.foo_inode_i | |
19 | Declare | |
20 | struct foo_inode_info { | |
21 | /* fs-private stuff */ | |
22 | struct inode vfs_inode; | |
23 | }; | |
24 | static inline struct foo_inode_info *FOO_I(struct inode *inode) | |
25 | { | |
26 | return list_entry(inode, struct foo_inode_info, vfs_inode); | |
27 | } | |
28 | ||
29 | Use FOO_I(inode) instead of &inode->u.foo_inode_i; | |
30 | ||
31 | Add foo_alloc_inode() and foo_destory_inode() - the former should allocate | |
32 | foo_inode_info and return the address of ->vfs_inode, the latter should free | |
33 | FOO_I(inode) (see in-tree filesystems for examples). | |
34 | ||
35 | Make them ->alloc_inode and ->destroy_inode in your super_operations. | |
36 | ||
37 | Keep in mind that now you need explicit initialization of private data - | |
38 | typically in ->read_inode() and after getting an inode from new_inode(). | |
39 | ||
40 | At some point that will become mandatory. | |
41 | ||
42 | --- | |
43 | [mandatory] | |
44 | ||
45 | Change of file_system_type method (->read_super to ->get_sb) | |
46 | ||
47 | ->read_super() is no more. Ditto for DECLARE_FSTYPE and DECLARE_FSTYPE_DEV. | |
48 | ||
49 | Turn your foo_read_super() into a function that would return 0 in case of | |
50 | success and negative number in case of error (-EINVAL unless you have more | |
51 | informative error value to report). Call it foo_fill_super(). Now declare | |
52 | ||
53 | struct super_block foo_get_sb(struct file_system_type *fs_type, | |
54 | int flags, const char *dev_name, void *data) | |
55 | { | |
56 | return get_sb_bdev(fs_type, flags, dev_name, data, ext2_fill_super); | |
57 | } | |
58 | ||
59 | (or similar with s/bdev/nodev/ or s/bdev/single/, depending on the kind of | |
60 | filesystem). | |
61 | ||
62 | Replace DECLARE_FSTYPE... with explicit initializer and have ->get_sb set as | |
63 | foo_get_sb. | |
64 | ||
65 | --- | |
66 | [mandatory] | |
67 | ||
68 | Locking change: ->s_vfs_rename_sem is taken only by cross-directory renames. | |
69 | Most likely there is no need to change anything, but if you relied on | |
70 | global exclusion between renames for some internal purpose - you need to | |
71 | change your internal locking. Otherwise exclusion warranties remain the | |
72 | same (i.e. parents and victim are locked, etc.). | |
73 | ||
74 | --- | |
75 | [informational] | |
76 | ||
77 | Now we have the exclusion between ->lookup() and directory removal (by | |
78 | ->rmdir() and ->rename()). If you used to need that exclusion and do | |
79 | it by internal locking (most of filesystems couldn't care less) - you | |
80 | can relax your locking. | |
81 | ||
82 | --- | |
83 | [mandatory] | |
84 | ||
85 | ->lookup(), ->truncate(), ->create(), ->unlink(), ->mknod(), ->mkdir(), | |
86 | ->rmdir(), ->link(), ->lseek(), ->symlink(), ->rename() | |
87 | and ->readdir() are called without BKL now. Grab it on entry, drop upon return | |
88 | - that will guarantee the same locking you used to have. If your method or its | |
89 | parts do not need BKL - better yet, now you can shift lock_kernel() and | |
90 | unlock_kernel() so that they would protect exactly what needs to be | |
91 | protected. | |
92 | ||
93 | --- | |
94 | [mandatory] | |
95 | ||
96 | BKL is also moved from around sb operations. ->write_super() Is now called | |
97 | without BKL held. BKL should have been shifted into individual fs sb_op | |
98 | functions. If you don't need it, remove it. | |
99 | ||
100 | --- | |
101 | [informational] | |
102 | ||
103 | check for ->link() target not being a directory is done by callers. Feel | |
104 | free to drop it... | |
105 | ||
106 | --- | |
107 | [informational] | |
108 | ||
109 | ->link() callers hold ->i_sem on the object we are linking to. Some of your | |
110 | problems might be over... | |
111 | ||
112 | --- | |
113 | [mandatory] | |
114 | ||
115 | new file_system_type method - kill_sb(superblock). If you are converting | |
116 | an existing filesystem, set it according to ->fs_flags: | |
117 | FS_REQUIRES_DEV - kill_block_super | |
118 | FS_LITTER - kill_litter_super | |
119 | neither - kill_anon_super | |
120 | FS_LITTER is gone - just remove it from fs_flags. | |
121 | ||
122 | --- | |
123 | [mandatory] | |
124 | ||
125 | FS_SINGLE is gone (actually, that had happened back when ->get_sb() | |
126 | went in - and hadn't been documented ;-/). Just remove it from fs_flags | |
127 | (and see ->get_sb() entry for other actions). | |
128 | ||
129 | --- | |
130 | [mandatory] | |
131 | ||
132 | ->setattr() is called without BKL now. Caller _always_ holds ->i_sem, so | |
133 | watch for ->i_sem-grabbing code that might be used by your ->setattr(). | |
134 | Callers of notify_change() need ->i_sem now. | |
135 | ||
136 | --- | |
137 | [recommended] | |
138 | ||
139 | New super_block field "struct export_operations *s_export_op" for | |
140 | explicit support for exporting, e.g. via NFS. The structure is fully | |
141 | documented at its declaration in include/linux/fs.h, and in | |
142 | Documentation/filesystems/Exporting. | |
143 | ||
144 | Briefly it allows for the definition of decode_fh and encode_fh operations | |
145 | to encode and decode filehandles, and allows the filesystem to use | |
146 | a standard helper function for decode_fh, and provide file-system specific | |
147 | support for this helper, particularly get_parent. | |
148 | ||
149 | It is planned that this will be required for exporting once the code | |
150 | settles down a bit. | |
151 | ||
152 | [mandatory] | |
153 | ||
154 | s_export_op is now required for exporting a filesystem. | |
155 | isofs, ext2, ext3, resierfs, fat | |
156 | can be used as examples of very different filesystems. | |
157 | ||
158 | --- | |
159 | [mandatory] | |
160 | ||
161 | iget4() and the read_inode2 callback have been superseded by iget5_locked() | |
162 | which has the following prototype, | |
163 | ||
164 | struct inode *iget5_locked(struct super_block *sb, unsigned long ino, | |
165 | int (*test)(struct inode *, void *), | |
166 | int (*set)(struct inode *, void *), | |
167 | void *data); | |
168 | ||
169 | 'test' is an additional function that can be used when the inode | |
170 | number is not sufficient to identify the actual file object. 'set' | |
171 | should be a non-blocking function that initializes those parts of a | |
172 | newly created inode to allow the test function to succeed. 'data' is | |
173 | passed as an opaque value to both test and set functions. | |
174 | ||
175 | When the inode has been created by iget5_locked(), it will be returned with | |
176 | the I_NEW flag set and will still be locked. read_inode has not been | |
177 | called so the file system still has to finalize the initialization. Once | |
178 | the inode is initialized it must be unlocked by calling unlock_new_inode(). | |
179 | ||
180 | The filesystem is responsible for setting (and possibly testing) i_ino | |
181 | when appropriate. There is also a simpler iget_locked function that | |
182 | just takes the superblock and inode number as arguments and does the | |
183 | test and set for you. | |
184 | ||
185 | e.g. | |
186 | inode = iget_locked(sb, ino); | |
187 | if (inode->i_state & I_NEW) { | |
188 | read_inode_from_disk(inode); | |
189 | unlock_new_inode(inode); | |
190 | } | |
191 | ||
192 | --- | |
193 | [recommended] | |
194 | ||
195 | ->getattr() finally getting used. See instances in nfs, minix, etc. | |
196 | ||
197 | --- | |
198 | [mandatory] | |
199 | ||
200 | ->revalidate() is gone. If your filesystem had it - provide ->getattr() | |
201 | and let it call whatever you had as ->revlidate() + (for symlinks that | |
202 | had ->revalidate()) add calls in ->follow_link()/->readlink(). | |
203 | ||
204 | --- | |
205 | [mandatory] | |
206 | ||
207 | ->d_parent changes are not protected by BKL anymore. Read access is safe | |
208 | if at least one of the following is true: | |
209 | * filesystem has no cross-directory rename() | |
210 | * dcache_lock is held | |
211 | * we know that parent had been locked (e.g. we are looking at | |
212 | ->d_parent of ->lookup() argument). | |
213 | * we are called from ->rename(). | |
214 | * the child's ->d_lock is held | |
215 | Audit your code and add locking if needed. Notice that any place that is | |
216 | not protected by the conditions above is risky even in the old tree - you | |
217 | had been relying on BKL and that's prone to screwups. Old tree had quite | |
218 | a few holes of that kind - unprotected access to ->d_parent leading to | |
219 | anything from oops to silent memory corruption. | |
220 | ||
221 | --- | |
222 | [mandatory] | |
223 | ||
224 | FS_NOMOUNT is gone. If you use it - just set MS_NOUSER in flags | |
225 | (see rootfs for one kind of solution and bdev/socket/pipe for another). | |
226 | ||
227 | --- | |
228 | [recommended] | |
229 | ||
230 | Use bdev_read_only(bdev) instead of is_read_only(kdev). The latter | |
231 | is still alive, but only because of the mess in drivers/s390/block/dasd.c. | |
232 | As soon as it gets fixed is_read_only() will die. | |
233 | ||
234 | --- | |
235 | [mandatory] | |
236 | ||
237 | ->permission() is called without BKL now. Grab it on entry, drop upon | |
238 | return - that will guarantee the same locking you used to have. If | |
239 | your method or its parts do not need BKL - better yet, now you can | |
240 | shift lock_kernel() and unlock_kernel() so that they would protect | |
241 | exactly what needs to be protected. | |
242 | ||
243 | --- | |
244 | [mandatory] | |
245 | ||
246 | ->statfs() is now called without BKL held. BKL should have been | |
247 | shifted into individual fs sb_op functions where it's not clear that | |
248 | it's safe to remove it. If you don't need it, remove it. | |
249 | ||
250 | --- | |
251 | [mandatory] | |
252 | ||
253 | is_read_only() is gone; use bdev_read_only() instead. | |
254 | ||
255 | --- | |
256 | [mandatory] | |
257 | ||
258 | destroy_buffers() is gone; use invalidate_bdev(). | |
259 | ||
260 | --- | |
261 | [mandatory] | |
262 | ||
263 | fsync_dev() is gone; use fsync_bdev(). NOTE: lvm breakage is | |
264 | deliberate; as soon as struct block_device * is propagated in a reasonable | |
265 | way by that code fixing will become trivial; until then nothing can be | |
266 | done. |