Hi Qu, Thank you for the patch! Yet something to improve: [auto build test ERROR on v5.9-rc5] [also build test ERROR on next-20200915] [cannot apply to kdave/for-next btrfs/next] [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] url: https://github.com/0day-ci/linux/commits/Qu-Wenruo/btrfs-add-read-only-su... base: 856deb866d16e29bd65952e0289066f6078af773 config: m68k-randconfig-r014-20200913 (attached as .config) compiler: m68k-linux-gcc (GCC) 9.3.0 reproduce (this is a W=1 build): wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=m68k If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): m68k-linux-ld: fs/btrfs/extent_io.o: in function `alloc_extent_buffer': m68k-linux-ld: fs/btrfs/extent_io.o: in function `release_extent_buffer': fs/btrfs/extent_io.c:5361: undefined reference to `__udivdi3' m68k-linux-ld: fs/btrfs/extent_io.o: in function `find_extent_buffer': fs/btrfs/extent_io.c:5145: undefined reference to `__udivdi3' # https://github.com/0day-ci/linux/commit/d68d61d0719a047c653dcee58952ec46f... git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Qu-Wenruo/btrfs-add-read-only-support-for-subpage-sector-size/20200915-133811 git checkout d68d61d0719a047c653dcee58952ec46f5db5d00 vim +5305 fs/btrfs/extent_io.c 5216 5217 struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info, 5218 u64 start) 5219 { 5220 unsigned long len = fs_info->nodesize; 5221 int num_pages; 5222 int i; 5223 unsigned long index = start >> PAGE_SHIFT; 5224 struct extent_buffer *eb; 5225 struct extent_buffer *exists = NULL; 5226 struct page *p; 5227 struct address_space *mapping = fs_info->btree_inode->i_mapping; 5228 int uptodate = 1; 5229 int ret; 5230 5231 if (!IS_ALIGNED(start, fs_info->sectorsize)) { 5232 btrfs_err(fs_info, "bad tree block start %llu", start); 5233 return ERR_PTR(-EINVAL); 5234 } 5235 5236 eb = find_extent_buffer(fs_info, start); 5237 if (eb) 5238 return eb; 5239 5240 eb = __alloc_extent_buffer(fs_info, start, len); 5241 if (!eb) 5242 return ERR_PTR(-ENOMEM); 5243 5244 num_pages = num_extent_pages(eb); 5245 for (i = 0; i < num_pages; i++, index++) { 5246 p = find_or_create_page(mapping, index, GFP_NOFS|__GFP_NOFAIL); 5247 if (!p) { 5248 exists = ERR_PTR(-ENOMEM); 5249 goto free_eb; 5250 } 5251 5252 spin_lock(&mapping->private_lock); 5253 if (PagePrivate(p)) { 5254 /* 5255 * We could have already allocated an eb for this page 5256 * and attached one so lets see if we can get a ref on 5257 * the existing eb, and if we can we know it's good and 5258 * we can just return that one, else we know we can just 5259 * overwrite page->private. 5260 */ 5261 exists = (struct extent_buffer *)p->private; 5262 if (atomic_inc_not_zero(&exists->refs)) { 5263 spin_unlock(&mapping->private_lock); 5264 unlock_page(p); 5265 put_page(p); 5266 mark_extent_buffer_accessed(exists, p); 5267 goto free_eb; 5268 } 5269 exists = NULL; 5270 5271 /* 5272 * Do this so attach doesn't complain and we need to 5273 * drop the ref the old guy had. 5274 */ 5275 ClearPagePrivate(p); 5276 WARN_ON(PageDirty(p)); 5277 put_page(p); 5278 } 5279 attach_extent_buffer_page(eb, p); 5280 spin_unlock(&mapping->private_lock); 5281 WARN_ON(PageDirty(p)); 5282 eb->pages[i] = p; 5283 if (!PageUptodate(p)) 5284 uptodate = 0; 5285 5286 /* 5287 * We can't unlock the pages just yet since the extent buffer 5288 * hasn't been properly inserted in the radix tree, this 5289 * opens a race with btree_releasepage which can free a page 5290 * while we are still filling in all pages for the buffer and 5291 * we could crash. 5292 */ 5293 } 5294 if (uptodate) 5295 set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags); 5296 again: 5297 ret = radix_tree_preload(GFP_NOFS); 5298 if (ret) { 5299 exists = ERR_PTR(ret); 5300 goto free_eb; 5301 } 5302 5303 spin_lock(&fs_info->buffer_lock); 5304 ret = radix_tree_insert(&fs_info->buffer_radix, 5306 spin_unlock(&fs_info->buffer_lock); 5307 radix_tree_preload_end(); 5308 if (ret == -EEXIST) { 5309 exists = find_extent_buffer(fs_info, start); 5310 if (exists) 5311 goto free_eb; 5312 else 5313 goto again; 5314 } 5315 /* add one reference for the tree */ 5316 check_buffer_tree_ref(eb); 5317 set_bit(EXTENT_BUFFER_IN_TREE, &eb->bflags); 5318 5319 /* 5320 * Now it's safe to unlock the pages because any calls to 5321 * btree_releasepage will correctly detect that a page belongs to a 5322 * live buffer and won't free them prematurely. 5323 */ 5324 for (i = 0; i < num_pages; i++) 5325 unlock_page(eb->pages[i]); 5326 return eb; 5327 5328 free_eb: 5329 WARN_ON(!atomic_dec_and_test(&eb->refs)); 5330 for (i = 0; i < num_pages; i++) { 5331 if (eb->pages[i]) 5332 unlock_page(eb->pages[i]); 5333 } 5334 5335 btrfs_release_extent_buffer(eb); 5336 return exists; 5337 } 5338 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org