Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | Changes since 2.5.0: |
2 | ||
3eb43f68 | 3 | --- |
1da177e4 LT |
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 | ||
3eb43f68 | 13 | --- |
1da177e4 LT |
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 | ||
3eb43f68 | 31 | Add foo_alloc_inode() and foo_destroy_inode() - the former should allocate |
1da177e4 LT |
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 | ||
12debc42 DH |
37 | Keep in mind that now you need explicit initialization of private data |
38 | typically between calling iget_locked() and unlocking the inode. | |
1da177e4 LT |
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 | ||
454e2398 DH |
53 | int foo_get_sb(struct file_system_type *fs_type, |
54 | int flags, const char *dev_name, void *data, struct vfsmount *mnt) | |
1da177e4 | 55 | { |
454e2398 DH |
56 | return get_sb_bdev(fs_type, flags, dev_name, data, foo_fill_super, |
57 | mnt); | |
1da177e4 LT |
58 | } |
59 | ||
60 | (or similar with s/bdev/nodev/ or s/bdev/single/, depending on the kind of | |
61 | filesystem). | |
62 | ||
63 | Replace DECLARE_FSTYPE... with explicit initializer and have ->get_sb set as | |
64 | foo_get_sb. | |
65 | ||
66 | --- | |
67 | [mandatory] | |
68 | ||
69 | Locking change: ->s_vfs_rename_sem is taken only by cross-directory renames. | |
70 | Most likely there is no need to change anything, but if you relied on | |
71 | global exclusion between renames for some internal purpose - you need to | |
72 | change your internal locking. Otherwise exclusion warranties remain the | |
73 | same (i.e. parents and victim are locked, etc.). | |
74 | ||
75 | --- | |
76 | [informational] | |
77 | ||
78 | Now we have the exclusion between ->lookup() and directory removal (by | |
79 | ->rmdir() and ->rename()). If you used to need that exclusion and do | |
80 | it by internal locking (most of filesystems couldn't care less) - you | |
81 | can relax your locking. | |
82 | ||
83 | --- | |
84 | [mandatory] | |
85 | ||
86 | ->lookup(), ->truncate(), ->create(), ->unlink(), ->mknod(), ->mkdir(), | |
87 | ->rmdir(), ->link(), ->lseek(), ->symlink(), ->rename() | |
88 | and ->readdir() are called without BKL now. Grab it on entry, drop upon return | |
89 | - that will guarantee the same locking you used to have. If your method or its | |
90 | parts do not need BKL - better yet, now you can shift lock_kernel() and | |
91 | unlock_kernel() so that they would protect exactly what needs to be | |
92 | protected. | |
93 | ||
94 | --- | |
95 | [mandatory] | |
96 | ||
97 | BKL is also moved from around sb operations. ->write_super() Is now called | |
98 | without BKL held. BKL should have been shifted into individual fs sb_op | |
99 | functions. If you don't need it, remove it. | |
100 | ||
101 | --- | |
102 | [informational] | |
103 | ||
104 | check for ->link() target not being a directory is done by callers. Feel | |
105 | free to drop it... | |
106 | ||
107 | --- | |
108 | [informational] | |
109 | ||
c2b38989 | 110 | ->link() callers hold ->i_mutex on the object we are linking to. Some of your |
1da177e4 LT |
111 | problems might be over... |
112 | ||
113 | --- | |
114 | [mandatory] | |
115 | ||
116 | new file_system_type method - kill_sb(superblock). If you are converting | |
117 | an existing filesystem, set it according to ->fs_flags: | |
118 | FS_REQUIRES_DEV - kill_block_super | |
119 | FS_LITTER - kill_litter_super | |
120 | neither - kill_anon_super | |
121 | FS_LITTER is gone - just remove it from fs_flags. | |
122 | ||
123 | --- | |
124 | [mandatory] | |
125 | ||
126 | FS_SINGLE is gone (actually, that had happened back when ->get_sb() | |
127 | went in - and hadn't been documented ;-/). Just remove it from fs_flags | |
128 | (and see ->get_sb() entry for other actions). | |
129 | ||
130 | --- | |
131 | [mandatory] | |
132 | ||
c2b38989 JJS |
133 | ->setattr() is called without BKL now. Caller _always_ holds ->i_mutex, so |
134 | watch for ->i_mutex-grabbing code that might be used by your ->setattr(). | |
135 | Callers of notify_change() need ->i_mutex now. | |
1da177e4 LT |
136 | |
137 | --- | |
138 | [recommended] | |
139 | ||
140 | New super_block field "struct export_operations *s_export_op" for | |
141 | explicit support for exporting, e.g. via NFS. The structure is fully | |
142 | documented at its declaration in include/linux/fs.h, and in | |
143 | Documentation/filesystems/Exporting. | |
144 | ||
145 | Briefly it allows for the definition of decode_fh and encode_fh operations | |
146 | to encode and decode filehandles, and allows the filesystem to use | |
147 | a standard helper function for decode_fh, and provide file-system specific | |
148 | support for this helper, particularly get_parent. | |
149 | ||
150 | It is planned that this will be required for exporting once the code | |
151 | settles down a bit. | |
152 | ||
153 | [mandatory] | |
154 | ||
155 | s_export_op is now required for exporting a filesystem. | |
156 | isofs, ext2, ext3, resierfs, fat | |
157 | can be used as examples of very different filesystems. | |
158 | ||
159 | --- | |
160 | [mandatory] | |
161 | ||
162 | iget4() and the read_inode2 callback have been superseded by iget5_locked() | |
163 | which has the following prototype, | |
164 | ||
165 | struct inode *iget5_locked(struct super_block *sb, unsigned long ino, | |
166 | int (*test)(struct inode *, void *), | |
167 | int (*set)(struct inode *, void *), | |
168 | void *data); | |
169 | ||
170 | 'test' is an additional function that can be used when the inode | |
171 | number is not sufficient to identify the actual file object. 'set' | |
172 | should be a non-blocking function that initializes those parts of a | |
173 | newly created inode to allow the test function to succeed. 'data' is | |
174 | passed as an opaque value to both test and set functions. | |
175 | ||
12debc42 DH |
176 | When the inode has been created by iget5_locked(), it will be returned with the |
177 | I_NEW flag set and will still be locked. The filesystem then needs to finalize | |
178 | the initialization. Once the inode is initialized it must be unlocked by | |
179 | calling unlock_new_inode(). | |
1da177e4 LT |
180 | |
181 | The filesystem is responsible for setting (and possibly testing) i_ino | |
182 | when appropriate. There is also a simpler iget_locked function that | |
183 | just takes the superblock and inode number as arguments and does the | |
184 | test and set for you. | |
185 | ||
186 | e.g. | |
b46980fe DH |
187 | inode = iget_locked(sb, ino); |
188 | if (inode->i_state & I_NEW) { | |
189 | err = read_inode_from_disk(inode); | |
190 | if (err < 0) { | |
191 | iget_failed(inode); | |
192 | return err; | |
193 | } | |
194 | unlock_new_inode(inode); | |
195 | } | |
196 | ||
197 | Note that if the process of setting up a new inode fails, then iget_failed() | |
198 | should be called on the inode to render it dead, and an appropriate error | |
199 | should be passed back to the caller. | |
1da177e4 LT |
200 | |
201 | --- | |
202 | [recommended] | |
203 | ||
204 | ->getattr() finally getting used. See instances in nfs, minix, etc. | |
205 | ||
206 | --- | |
207 | [mandatory] | |
208 | ||
209 | ->revalidate() is gone. If your filesystem had it - provide ->getattr() | |
210 | and let it call whatever you had as ->revlidate() + (for symlinks that | |
211 | had ->revalidate()) add calls in ->follow_link()/->readlink(). | |
212 | ||
213 | --- | |
214 | [mandatory] | |
215 | ||
216 | ->d_parent changes are not protected by BKL anymore. Read access is safe | |
217 | if at least one of the following is true: | |
218 | * filesystem has no cross-directory rename() | |
219 | * dcache_lock is held | |
220 | * we know that parent had been locked (e.g. we are looking at | |
221 | ->d_parent of ->lookup() argument). | |
222 | * we are called from ->rename(). | |
223 | * the child's ->d_lock is held | |
224 | Audit your code and add locking if needed. Notice that any place that is | |
225 | not protected by the conditions above is risky even in the old tree - you | |
226 | had been relying on BKL and that's prone to screwups. Old tree had quite | |
227 | a few holes of that kind - unprotected access to ->d_parent leading to | |
228 | anything from oops to silent memory corruption. | |
229 | ||
230 | --- | |
231 | [mandatory] | |
232 | ||
233 | FS_NOMOUNT is gone. If you use it - just set MS_NOUSER in flags | |
234 | (see rootfs for one kind of solution and bdev/socket/pipe for another). | |
235 | ||
236 | --- | |
237 | [recommended] | |
238 | ||
239 | Use bdev_read_only(bdev) instead of is_read_only(kdev). The latter | |
240 | is still alive, but only because of the mess in drivers/s390/block/dasd.c. | |
241 | As soon as it gets fixed is_read_only() will die. | |
242 | ||
243 | --- | |
244 | [mandatory] | |
245 | ||
246 | ->permission() is called without BKL now. Grab it on entry, drop upon | |
247 | return - that will guarantee the same locking you used to have. If | |
248 | your method or its parts do not need BKL - better yet, now you can | |
249 | shift lock_kernel() and unlock_kernel() so that they would protect | |
250 | exactly what needs to be protected. | |
251 | ||
252 | --- | |
253 | [mandatory] | |
254 | ||
255 | ->statfs() is now called without BKL held. BKL should have been | |
256 | shifted into individual fs sb_op functions where it's not clear that | |
257 | it's safe to remove it. If you don't need it, remove it. | |
258 | ||
259 | --- | |
260 | [mandatory] | |
261 | ||
262 | is_read_only() is gone; use bdev_read_only() instead. | |
263 | ||
264 | --- | |
265 | [mandatory] | |
266 | ||
267 | destroy_buffers() is gone; use invalidate_bdev(). | |
268 | ||
269 | --- | |
270 | [mandatory] | |
271 | ||
272 | fsync_dev() is gone; use fsync_bdev(). NOTE: lvm breakage is | |
273 | deliberate; as soon as struct block_device * is propagated in a reasonable | |
274 | way by that code fixing will become trivial; until then nothing can be | |
275 | done. |