Hi, On 08/17/2017 08:43 PM, Chris Murphy wrote: > # btrfs sub create test1 > Create subvolume './test1' > # btrfs sub create test1/test2 > Create subvolume 'test1/test2' > # btrfs sub snap test1 test1.snap > Create a snapshot of 'test1' in './test1.snap' > # btrfs fi du -s test1 > Total Exclusive Set shared Filename > 0.00B 0.00B 0.00B test1 > # btrfs fi du -s test1.snap > Total Exclusive Set shared Filename > ERROR: cannot check space of 'test1.snap': Inappropriate ioctl for device > # >
tanks for the test case. Now I was able to reproduce the problem. The bug(s) are two: 1) to get the treeid of the files/directory, the function lookup_path_rootid() is used, which behaves strangely when it is called on a directory that is BTRFS_EMPTY_SUBVOL_DIR_OBJECTID. In fact this function is commented as following: [....] /* * For a given: * - file or directory return the containing tree root id * - subvolume return its own tree id * - BTRFS_EMPTY_SUBVOL_DIR_OBJECTID (directory with ino == 2) the result is * undefined and function returns -1 */ int lookup_path_rootid(int fd, u64 *rootid) { [....] The caller (du_add_file()) doesn't consider this case. 2) in the function du_walk_dir(), an error returned by du_add_file() is ignored, but the return value is not reset. So if the last entry has ino BTRFS_EMPTY_SUBVOL_DIR_OBJECTID (directory with ino == 2) an error is returned. But if there is another directory item no error is returned ! See the following tests cases: # btrfs sub create test1 # btrfs sub create test1/test2 # btrfs sub snap test1 test1.snap # btrfs fi du -s test1 Total Exclusive Set shared Filename 0.00B 0.00B 0.00B test1 # btrfs fi du -s test1.snap Total Exclusive Set shared Filename ERROR: cannot check space of 'test1.snap': Inappropriate ioctl for device But if you add *another* file/dir in test1.snap you got: # mkdir test1.snap/dir # btrfs fi du -s test1.snap Total Exclusive Set shared Filename 0.00B 0.00B 0.00B test1.snap The error disappear ! Patches will follow shortly > > # uname -r > 4.13.0-0.rc4.git1.1.fc27.x86_64 > # rpm -q btrfs-progs > btrfs-progs-4.12-1.fc27.x86_64 > > > ---- > Chris Murphy > -- gpg @keyserver.linux.it: Goffredo Baroncelli <kreijackATinwind.it> Key fingerprint BBF5 1610 0B64 DAC6 5F7D 17B2 0EDA 9B37 8B82 E0B5 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html