Zach Brown bdb76ef5a4 dio: fix cache invalidation after sync writes ... Commit commit 65b8291c40 ("dio: invalidate clean pages before dio write") introduced a bug which stopped dio from ever invalidating the page cache after writes. It still invalidated it before writes so most users were fine. Karl Schendel reported ( http://lkml.org/lkml/2007/10/26/481 ) hitting this bug when he had a buffered reader immediately reading file data after an O_DIRECT wirter had written the data. The kernel issued read-ahead beyond the position of the reader which overlapped with the O_DIRECT writer. The failure to invalidate after writes caused the reader to see stale data from the read-ahead. The following patch is originally from Karl. The following commentary is his: The below 3rd try takes on your suggestion of just invalidating no matter what the retval from the direct_IO call. I ran it thru the test-case several times and it has worked every time. The post-invalidate is probably still too early for async-directio, but I don't have a testcase for that; just sync. And, this won't be any worse in the async case. I added a test to the aio-dio-regress repository which mimics Karl's IO pattern. It verifed the bad behaviour and that the patch fixed it. I agree with Karl, this still doesn't help the case where a buffered reader follows an AIO O_DIRECT writer. That will require a bit more work. This gives up on the idea of returning EIO to indicate to userspace that stale data remains if the invalidation failed. Signed-off-by: Zach Brown <zach.brown@oracle.com> Cc: Karl Schendel <kschendel@datallegro.com> Cc: Benjamin LaHaise <bcrl@kvack.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Leonid Ananiev <leonid.i.ananiev@linux.intel.com> Cc: Chris Mason <chris.mason@oracle.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>		2007-10-30 12:14:06 -07:00
..
allocpercpu.c
backing-dev.c
bootmem.c
bounce.c
fadvise.c
filemap_xip.c
filemap.c	dio: fix cache invalidation after sync writes	2007-10-30 12:14:06 -07:00
fremap.c
highmem.c
hugetlb.c
internal.h
Kconfig
madvise.c
Makefile
memory_hotplug.c
memory.c
mempolicy.c
mempool.c
migrate.c
mincore.c
mlock.c
mmap.c
mmzone.c
mprotect.c
mremap.c
msync.c
nommu.c
oom_kill.c
page_alloc.c
page_io.c
page_isolation.c
page-writeback.c
pdflush.c
prio_tree.c
quicklist.c
readahead.c
rmap.c
shmem_acl.c
shmem.c	fix tmpfs BUG and AOP_WRITEPAGE_ACTIVATE	2007-10-30 08:06:55 -07:00
slab.c
slob.c
slub.c
sparse-vmemmap.c	mm/sparse-vmemmap.c: make sure init_mm is included	2007-10-30 08:06:55 -07:00
sparse.c
swap_state.c
swap.c
swapfile.c
thrash.c
tiny-shmem.c
truncate.c
util.c
vmalloc.c
vmscan.c
vmstat.c