Theodore Ts'o <tytso@xxxxxxx> writes: > On Fri, Oct 17, 2014 at 05:25:34PM +0400, Dmitry Monakhov wrote: >> It is rediculus practice to scan inode block by block, this technique >> applicable only for old indirect files. This takes signifficant amount >> of time for really large files. Let's reuse ext4_fiemap which already >> traverse inode-tree in most optimal meaner. >> >> TESTCASE: >> ftruncate64(fd, 0); >> ftruncate64(fd, 1ULL << 40); >> /* lseek will spin very long time */ >> lseek64(fd, 0, SEEK_DATA); >> lseek64(fd, 0, SEEK_HOLE); >> >> >> Original report: https://lkml.org/lkml/2014/10/16/620 >> >> ################################## >> BTW: Why do we need i_mutex here? >> >> Signed-off-by: Dmitry Monakhov <dmonakhov@xxxxxxxxxx> > > Note: this patch causes generic/285 to loop forever in inline-data > mode. My guess is in the special case handling of inline data in > ext4_fiemap not playing well with this change, but I haven't had a > chance to look deeply into this yet. FYI: inline_data feature is fatally broken 1) incorrect lock order (journal_start vs grab_cache_page_write_begin ) ext4_da_write_inline_data_begin ->start_journal ->grab_cache_page_write_begin ->pagecache_get_page -> FS_REENTRANCE->DEADLOCK 2) ext4_inline_data_fiemap(0 ignores start and len arguments from ext4_filemap() which obviously result in endless loop for anyone who want to use fiemap for inline files (which my patch try to do) I'll send patches soon. > > - Ted
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