linux/mm
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 Slab allocators: Replace explicit zeroing with __GFP_ZERO 2007-07-17 10:23:02 -07:00
backing-dev.c mm: per device dirty threshold 2007-10-17 08:42:45 -07:00
bootmem.c [PATCH] remove EXPORT_UNUSED_SYMBOL'ed symbols 2006-12-07 08:39:44 -08:00
bounce.c block: Initial support for data-less (or empty) barrier support 2007-10-16 11:03:56 +02:00
fadvise.c [PATCH] mm: change uses of f_{dentry,vfsmnt} to use f_path 2006-12-08 08:28:43 -08:00
filemap_xip.c mm: write iovec cleanup 2007-10-16 09:42:54 -07:00
filemap.c dio: fix cache invalidation after sync writes 2007-10-30 12:14:06 -07:00
fremap.c remap_file_pages: kernel-doc corrections 2007-10-17 08:43:07 -07:00
highmem.c Create the ZONE_MOVABLE zone 2007-07-17 10:22:59 -07:00
hugetlb.c spelling fixes: mm/ 2007-10-20 01:27:18 +02:00
internal.h Breakout page_order() to internal.h to avoid special knowledge of the buddy allocator 2007-10-16 09:43:01 -07:00
Kconfig small documentation fixes 2007-10-20 02:46:58 +02:00
madvise.c speed up madvise_need_mmap_write() usage 2007-07-16 09:05:36 -07:00
Makefile memory unplug: page isolation 2007-10-16 09:43:02 -07:00
memory_hotplug.c memory hotplug: rearrange memory hotplug notifier 2007-10-22 08:13:17 -07:00
memory.c spelling fixes: mm/ 2007-10-20 01:27:18 +02:00
mempolicy.c Uninline find_task_by_xxx set of functions 2007-10-19 11:53:40 -07:00
mempool.c spelling fixes: mm/ 2007-10-20 01:27:18 +02:00
migrate.c Typo fixes retrun -> return 2007-10-20 02:13:26 +02:00
mincore.c [PATCH] mincore: vma crossing fix 2007-02-15 09:57:03 -08:00
mlock.c do not limit locked memory when RLIMIT_MEMLOCK is RLIM_INFINITY 2007-07-16 09:05:37 -07:00
mmap.c fix mprotect vma_wants_writenotify prot 2007-10-23 08:32:06 -07:00
mmzone.c [PATCH] remove EXPORT_UNUSED_SYMBOL'ed symbols 2006-12-07 08:39:44 -08:00
mprotect.c fix mprotect vma_wants_writenotify prot 2007-10-23 08:32:06 -07:00
mremap.c sparse pointer use of zero as null 2007-10-18 14:37:31 -07:00
msync.c Detach sched.h from mm.h 2007-05-21 09:18:19 -07:00
nommu.c NOMMU: mm/nommu.c needs linux/module.h 2007-10-29 07:53:26 -07:00
oom_kill.c oom_kill bug 2007-10-20 15:04:06 -07:00
page_alloc.c spelling fixes: mm/ 2007-10-20 01:27:18 +02:00
page_io.c Drop 'size' argument from bio_endio and bi_end_io 2007-10-10 09:25:57 +02:00
page_isolation.c memory unplug: page isolation 2007-10-16 09:43:02 -07:00
page-writeback.c spelling fixes: mm/ 2007-10-20 01:27:18 +02:00
pdflush.c Freezer: make kernel threads nonfreezable by default 2007-07-17 10:23:02 -07:00
prio_tree.c spelling fixes: mm/ 2007-10-20 01:27:18 +02:00
quicklist.c Quicklists for page table pages 2007-05-07 12:12:54 -07:00
readahead.c mm: bdi init hooks 2007-10-17 08:42:45 -07:00
rmap.c mm: document tree_lock->zone.lock lockorder 2007-10-17 08:42:46 -07:00
shmem_acl.c [PATCH] Fix typos in mm/shmem_acl.c 2006-10-11 11:14:23 -07:00
shmem.c fix tmpfs BUG and AOP_WRITEPAGE_ACTIVATE 2007-10-30 08:06:55 -07:00
slab.c spelling fixes: mm/ 2007-10-20 01:27:18 +02:00
slob.c Slab API: remove useless ctor parameter and reorder parameters 2007-10-17 08:42:45 -07:00
slub.c missing atomic_read_long() in slub.c 2007-10-29 07:41:32 -07:00
sparse-vmemmap.c mm/sparse-vmemmap.c: make sure init_mm is included 2007-10-30 08:06:55 -07:00
sparse.c Revert "x86_64: allocate sparsemem memmap above 4G" 2007-10-29 14:05:37 -07:00
swap_state.c mm: clarify __add_to_swap_cache locking 2007-10-16 09:42:53 -07:00
swap.c spelling fixes: mm/ 2007-10-20 01:27:18 +02:00
swapfile.c Replace CONFIG_SOFTWARE_SUSPEND with CONFIG_HIBERNATION 2007-07-29 16:45:38 -07:00
thrash.c Bug in mm/thrash.c function grab_swap_token() 2007-05-11 08:29:32 -07:00
tiny-shmem.c r/o bind mounts: filesystem helpers for custom 'struct file's 2007-10-17 08:43:04 -07:00
truncate.c Drop some headers from mm.h 2007-10-17 08:42:55 -07:00
util.c Slab allocators: fail if ksize is called with a NULL parameter 2007-10-16 09:42:53 -07:00
vmalloc.c spelling fixes: mm/ 2007-10-20 01:27:18 +02:00
vmscan.c spelling fixes: mm/ 2007-10-20 01:27:18 +02:00
vmstat.c oom: change all_unreclaimable zone member to flags 2007-10-17 08:42:45 -07:00