Re: [PATCH 2/7] vfs: add inode iteration superblock method

kernel test robot
2024-10-04T09:54:13Z

Hi Dave,

kernel test robot noticed the following build warnings:

[auto build test WARNING on brauner-vfs/vfs.all]
[also build test WARNING on xfs-linux/for-next axboe-block/for-next linus/master v6.12-rc1 next-20241004]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url: https://github.com/intel-lab-lkp/linux/commits/Dave-Chinner/vfs-replace-invalidate_inodes-with-evict_inodes/20241002-094254
base: https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git vfs.all
patch link: https://lore.kernel.org/r/20241002014017.3801899-3-david%40fromorbit.com
patch subject: [PATCH 2/7] vfs: add inode iteration superblock method
config: openrisc-allnoconfig (https://download.01.org/0day-ci/archive/20241004/202410041724.REiCiIEQ-lkp@intel.com/config)
compiler: or1k-linux-gcc (GCC) 14.1.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20241004/202410041724.REiCiIEQ-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202410041724.REiCiIEQ-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> fs/super.c:183: warning: Function parameter or struct member 'private_data' not described in 'super_iter_inodes'
>> fs/super.c:183: warning: Function parameter or struct member 'flags' not described in 'super_iter_inodes'
>> fs/super.c:241: warning: bad line:
>> fs/super.c:260: warning: Function parameter or struct member 'private_data' not described in 'super_iter_inodes_unsafe'

vim +183 fs/super.c

169
170 /**
171 * super_iter_inodes - iterate all the cached inodes on a superblock
172 * @sb: superblock to iterate
173 * @iter_fn: callback to run on every inode found.
174 *
175 * This function iterates all cached inodes on a superblock that are not in
176 * the process of being initialised or torn down. It will run @iter_fn() with
177 * a valid, referenced inode, so it is safe for the caller to do anything
178 * it wants with the inode except drop the reference the iterator holds.
179 *
180 */
181 int super_iter_inodes(struct super_block *sb, ino_iter_fn iter_fn,
182 void *private_data, int flags)
> 183 {
184 struct inode *inode, *old_inode = NULL;
185 int ret = 0;
186
187 spin_lock(&sb->s_inode_list_lock);
188 list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
189 spin_lock(&inode->i_lock);
190 if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) {
191 spin_unlock(&inode->i_lock);
192 continue;
193 }
194
195 /*
196 * Skip over zero refcount inode if the caller only wants
197 * referenced inodes to be iterated.
198 */
199 if ((flags & INO_ITER_REFERENCED) &&
200 !atomic_read(&inode->i_count)) {
201 spin_unlock(&inode->i_lock);
202 continue;
203 }
204
205 __iget(inode);
206 spin_unlock(&inode->i_lock);
207 spin_unlock(&sb->s_inode_list_lock);
208 iput(old_inode);
209
210 ret = iter_fn(inode, private_data);
211
212 old_inode = inode;
213 if (ret == INO_ITER_ABORT) {
214 ret = 0;
215 break;
216 }
217 if (ret < 0)
218 break;
219
220 cond_resched();
221 spin_lock(&sb->s_inode_list_lock);
222 }
223 spin_unlock(&sb->s_inode_list_lock);
224 iput(old_inode);
225 return ret;
226 }
227
228 /**
229 * super_iter_inodes_unsafe - unsafely iterate all the inodes on a superblock
230 * @sb: superblock to iterate
231 * @iter_fn: callback to run on every inode found.
232 *
233 * This is almost certainly not the function you want. It is for internal VFS
234 * operations only. Please use super_iter_inodes() instead. If you must use
235 * this function, please add a comment explaining why it is necessary and the
236 * locking that makes it safe to use this function.
237 *
238 * This function iterates all cached inodes on a superblock that are attached to
239 * the superblock. It will pass each inode to @iter_fn unlocked and without
240 * having performed any existences checks on it.
> 241
242 * @iter_fn must perform all necessary state checks on the inode itself to
243 * ensure safe operation. super_iter_inodes_unsafe() only guarantees that the
244 * inode exists and won't be freed whilst the callback is running.
245 *
246 * @iter_fn must not block. It is run in an atomic context that is not allowed
247 * to sleep to provide the inode existence guarantees. If the callback needs to
248 * do blocking operations it needs to track the inode itself and defer those
249 * operations until after the iteration completes.
250 *
251 * @iter_fn must provide conditional reschedule checks itself. If rescheduling
252 * or deferred processing is needed, it must return INO_ITER_ABORT to return to
253 * the high level function to perform those operations. It can then restart the
254 * iteration again. The high level code must provide forwards progress
255 * guarantees if they are necessary.
256 *
257 */
258 void super_iter_inodes_unsafe(struct super_block *sb, ino_iter_fn iter_fn,
259 void *private_data)
> 260 {
261 struct inode *inode;
262 int ret;
263
264 rcu_read_lock();
265 spin_lock(&sb->s_inode_list_lock);
266 list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
267 ret = iter_fn(inode, private_data);
268 if (ret == INO_ITER_ABORT)
269 break;
270 }
271 spin_unlock(&sb->s_inode_list_lock);
272 rcu_read_unlock();
273 }
274

--
0-DAY CI Kernel Test Service