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authorNick Piggin <npiggin@suse.de>2009-01-06 14:40:22 -0800
committerGreg Kroah-Hartman <gregkh@suse.de>2009-01-24 16:36:28 -0800
commit2bfdd01129aa5dc52939a9d6ba8012c27ed9f5fa (patch)
treea6521e577308b594289195ce9951074c42444859
parentebf8d00d3ffadbba82ea19f9c6e273c8fb09c8a8 (diff)
downloadlinux-linaro-stable-2bfdd01129aa5dc52939a9d6ba8012c27ed9f5fa.tar.gz
mm: direct IO starvation improvement
commit 48b47c561e41525061b5bc0cfd67d6367fd11dc4 upstream. Direct IO can invalidate and sync a lot of pagecache pages in the mapping. A 4K direct IO will actually try to sync and/or invalidate the pagecache of the entire file, for example (which might be many GB or TB large). Improve this by doing range syncs. Also, memory no longer has to be unmapped to catch the dirty bits for syncing, as dirty bits would remain coherent due to dirty mmap accounting. This fixes the immediate DM deadlocks when doing direct IO reads to block device with a mounted filesystem, if only by papering over the problem somewhat rather than addressing the fsync starvation cases. Signed-off-by: Nick Piggin <npiggin@suse.de> Reviewed-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--mm/filemap.c16
1 files changed, 5 insertions, 11 deletions
diff --git a/mm/filemap.c b/mm/filemap.c
index 0b38278..8a477d3 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1304,7 +1304,8 @@ generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
goto out; /* skip atime */
size = i_size_read(inode);
if (pos < size) {
- retval = filemap_write_and_wait(mapping);
+ retval = filemap_write_and_wait_range(mapping, pos,
+ pos + iov_length(iov, nr_segs) - 1);
if (!retval) {
retval = mapping->a_ops->direct_IO(READ, iocb,
iov, pos, nr_segs);
@@ -2117,18 +2118,10 @@ generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
if (count != ocount)
*nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count);
- /*
- * Unmap all mmappings of the file up-front.
- *
- * This will cause any pte dirty bits to be propagated into the
- * pageframes for the subsequent filemap_write_and_wait().
- */
write_len = iov_length(iov, *nr_segs);
end = (pos + write_len - 1) >> PAGE_CACHE_SHIFT;
- if (mapping_mapped(mapping))
- unmap_mapping_range(mapping, pos, write_len, 0);
- written = filemap_write_and_wait(mapping);
+ written = filemap_write_and_wait_range(mapping, pos, pos + write_len - 1);
if (written)
goto out;
@@ -2519,7 +2512,8 @@ generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
* the file data here, to try to honour O_DIRECT expectations.
*/
if (unlikely(file->f_flags & O_DIRECT) && written)
- status = filemap_write_and_wait(mapping);
+ status = filemap_write_and_wait_range(mapping,
+ pos, pos + written - 1);
return written ? written : status;
}