The patch titled
mm: direct IO starvation improvement
has been added to the -mm tree. Its filename is
mm-direct-io-starvation-improvement.patch
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------------------------------------------------------
Subject: mm: direct IO starvation improvement
From: Nick Piggin <npiggin@xxxxxxx>
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@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/filemap.c | 16 +++++-----------
1 file changed, 5 insertions(+), 11 deletions(-)
diff -puN mm/filemap.c~mm-direct-io-starvation-improvement mm/filemap.c
--- a/mm/filemap.c~mm-direct-io-starvation-improvement
+++ a/mm/filemap.c
@@ -1369,7 +1369,8 @@ generic_file_aio_read(struct kiocb *iocb
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);
@@ -2137,18 +2138,10 @@ generic_file_direct_write(struct kiocb *
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;
@@ -2363,7 +2356,8 @@ generic_file_buffered_write(struct kiocb
* 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;
}
_
Patches currently in -mm which might be from npiggin@xxxxxxx are
linux-next.patch
mm-dont-mark_page_accessed-in-fault-path.patch
mm-dont-mark_page_accessed-in-shmem_fault.patch
mm-invoke-oom-killer-from-page-fault.patch
mm-invoke-oom-killer-from-page-fault-fix.patch
mm-invoke-oom-killer-from-page-fault-fix-fix-2.patch
mm-write_cache_pages-cyclic-fix.patch
mm-write_cache_pages-cyclic-fix-fix.patch
mm-write_cache_pages-early-loop-termination.patch
mm-write_cache_pages-writepage-error-fix.patch
mm-write_cache_pages-integrity-fix.patch
mm-write_cache_pages-cleanups.patch
mm-write_cache_pages-optimise-page-cleaning.patch
mm-write_cache_pages-terminate-quickly.patch
mm-write_cache_pages-more-terminate-quickly.patch
mm-do_sync_mapping_range-integrity-fix.patch
mm-get-rid-of-pagevec_release_nonlru.patch
mm-more-likely-reclaim-madv_sequential-mappings.patch
mm-vmalloc-tweak-failure-printk.patch
mm-vmalloc-improve-vmallocinfo.patch
mm-vmalloc-use-mutex-for-purge.patch
mm-vmalloc-make-lazy-unmapping-configurable.patch
fs-truncate-blocks-outside-i_size-after-o_direct-write-error.patch
fs-truncate-blocks-outside-i_size-after-o_direct-write-error-fix.patch
hugetlb-unsigned-ret-cannot-be-negative.patch
page_fault-retry-with-nopage_retry.patch
page_fault-retry-with-nopage_retry-fix.patch
page_fault-retry-with-nopage_retry-fix-fix.patch
mm-direct-io-starvation-improvement.patch
fs-remove-wb_sync_hold.patch
fs-sync_sb_inodes-fix.patch
fs-sys_sync-fix.patch
radix-tree-gang-set-if-tagged-operation.patch
mm-fsync-livelock-avoidance.patch
reiser4.patch
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