On 08/21/2014 09:08 AM, Christoph Hellwig wrote: > On Thu, Aug 21, 2014 at 03:09:09PM +1000, Dave Chinner wrote: >> From: Dave Chinner <dchinner@xxxxxxxxxx> >> >> generic/263 is failing fsx at this point with a page spanning >> EOF that cannot be invalidated. The operations are: >> >> 1190 mapwrite 0x52c00 thru 0x5e569 (0xb96a bytes) >> 1191 mapread 0x5c000 thru 0x5d636 (0x1637 bytes) >> 1192 write 0x5b600 thru 0x771ff (0x1bc00 bytes) >> >> where 1190 extents EOF from 0x54000 to 0x5e569. When the direct IO >> write attempts to invalidate the cached page over this range, it >> fails with -EBUSY and so we fire this assert: >> >> XFS: Assertion failed: ret < 0 || ret == count, file: fs/xfs/xfs_file.c, line: 676 >> >> because the kernel is trying to fall back to buffered IO on the >> direct IO path (which XFS does not do). >> >> The real question is this: Why can't that page be invalidated after >> it has been written to disk an cleaned? >> >> Well, there's data on the first two buffers in the page (1k block >> size, 4k page), but the third buffer on the page (i.e. beyond EOF) >> is failing drop_buffers because it's bh->b_state == 0x3, which is >> BH_Uptodate | BH_Dirty. IOWs, there's dirty buffers beyond EOF. Say >> what? >> >> OK, set_buffer_dirty() is called on all buffers from >> __set_page_buffers_dirty(), regardless of whether the buffer is >> beyond EOF or not, which means that when we get to ->writepage, >> we have buffers marked dirty beyond EOF that we need to clean. >> So, we need to implement our own .set_page_dirty method that >> doesn't dirty buffers beyond EOF. > > Shouldn't this be fixed in __set_page_buffers_dirty itself? This > doesn't seem an XFS-specific issue. > block_write_full_page() is invalidating buffers past eof. Probably because we used to be able to dirty buffers without holding the page lock, and it's much easier to trust i_size at writepage time. I think we have the page locked for all the dirties now, so this isn't as important as in the past? -chris -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
