Hello David Howells,
Commit 74e797d79cf1 ("mm: Provide a means of invalidation without
using launder_folio") from Mar 27, 2024 (linux-next), leads to the
following Smatch static checker warning:
mm/filemap.c:4229 filemap_invalidate_inode()
error: we previously assumed 'mapping' could be null (see line 4200)
mm/filemap.c
4192 int filemap_invalidate_inode(struct inode *inode, bool flush,
4193 loff_t start, loff_t end)
4194 {
4195 struct address_space *mapping = inode->i_mapping;
4196 pgoff_t first = start >> PAGE_SHIFT;
4197 pgoff_t last = end >> PAGE_SHIFT;
4198 pgoff_t nr = end == LLONG_MAX ? ULONG_MAX : last - first + 1;
4199
4200 if (!mapping || !mapping->nrpages || end < start)
^^^^^^^^
If mapping is NULL
4201 goto out;
4202
4203 /* Prevent new folios from being added to the inode. */
4204 filemap_invalidate_lock(mapping);
4205
4206 if (!mapping->nrpages)
4207 goto unlock;
4208
4209 unmap_mapping_pages(mapping, first, nr, false);
4210
4211 /* Write back the data if we're asked to. */
4212 if (flush) {
4213 struct writeback_control wbc = {
4214 .sync_mode = WB_SYNC_ALL,
4215 .nr_to_write = LONG_MAX,
4216 .range_start = start,
4217 .range_end = end,
4218 };
4219
4220 filemap_fdatawrite_wbc(mapping, &wbc);
4221 }
4222
4223 /* Wait for writeback to complete on all folios and discard. */
4224 truncate_inode_pages_range(mapping, start, end);
4225
4226 unlock:
4227 filemap_invalidate_unlock(mapping);
4228 out:
4229 return filemap_check_errors(mapping);
^^^^^^^
Then we're toasted. The errors from filemap_check_errors() aren't what
I expected.
4230 }
regards,
dan carpenter
