Date:	Sat, 31 Mar 2007 22:10:34 -0700
From:	akpm@...ux-foundation.org
To:	mm-commits@...r.kernel.org
Cc:	akpm@...ux-foundation.org, dev@...nvz.org, dmonakhov@...nvz.org,
	kenneth.w.chen@...el.com, linux-ext4@...r.kernel.org,
	mingo@...e.hu, saw@...ru, stable@...nel.org
Subject: + revert-retries-in-ext3_prepare_write-violate-ordering-requirements.patch added to -mm tree


The patch titled
     revert "retries in ext3_prepare_write() violate ordering requirements"
has been added to the -mm tree.  Its filename is
     revert-retries-in-ext3_prepare_write-violate-ordering-requirements.patch

*** Remember to use Documentation/SubmitChecklist when testing your code ***

See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this

------------------------------------------------------
Subject: revert "retries in ext3_prepare_write() violate ordering requirements"
From: Andrew Morton <akpm@...ux-foundation.org>

Revert e92a4d595b464c4aae64be39ca61a9ffe9c8b278.

Dmitry points out

"When we block_prepare_write() failed while ext3_prepare_write() we jump to
 "failure" label and call ext3_prepare_failure() witch search last mapped bh
 and invoke commit_write untill it.  This is wrong!!  because some bh from
 begining to the last mapped bh may be not uptodate.  As a result we commit to
 disk not uptodate page content witch contains garbage from previous usage."

and

"Unexpected file size increasing."

   Call trace the same as it was in first issue but result is different. 
   For example we have file with i_size is zero.  we want write two blocks ,
   but fs has only one free block.

   ->ext3_prepare_write(...from == 0, to == 2048)
     retry:
     ->block_prepare_write() == -ENOSPC# we failed but allocated one block here.
     ->ext3_prepare_failure()
       ->commit_write( from == 0, to == 1024) # after this i_size becomes 1024 :)
     if (ret == -ENOSPC && ext3_should_retry_alloc(inode->i_sb, &retries))
        goto retry;

   Finally when all retries will be spended ext3_prepare_failure return
   -ENOSPC, but i_size was increased and later block trimm procedures can't
   help here.

We don't appear to have the horsepower to fix these issues, so let's put
things back the way they were for now.

Cc: Kirill Korotaev <dev@...nvz.org>
Cc: Ingo Molnar <mingo@...e.hu>
Cc: Ken Chen <kenneth.w.chen@...el.com>
Cc: Andrey Savochkin <saw@...ru>
Cc: <linux-ext4@...r.kernel.org>
Cc: Dmitriy Monakhov <dmonakhov@...nvz.org>
Cc: <stable@...nel.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
---

 fs/ext3/inode.c |   85 +++++-----------------------------------------
 1 file changed, 10 insertions(+), 75 deletions(-)

diff -puN fs/ext3/inode.c~revert-retries-in-ext3_prepare_write-violate-ordering-requirements fs/ext3/inode.c
--- a/fs/ext3/inode.c~revert-retries-in-ext3_prepare_write-violate-ordering-requirements
+++ a/fs/ext3/inode.c
@@ -1148,102 +1148,37 @@ static int do_journal_get_write_access(h
 	return ext3_journal_get_write_access(handle, bh);
 }
 
-/*
- * The idea of this helper function is following:
- * if prepare_write has allocated some blocks, but not all of them, the
- * transaction must include the content of the newly allocated blocks.
- * This content is expected to be set to zeroes by block_prepare_write().
- * 2006/10/14  SAW
- */
-static int ext3_prepare_failure(struct file *file, struct page *page,
-				unsigned from, unsigned to)
-{
-	struct address_space *mapping;
-	struct buffer_head *bh, *head, *next;
-	unsigned block_start, block_end;
-	unsigned blocksize;
-	int ret;
-	handle_t *handle = ext3_journal_current_handle();
-
-	mapping = page->mapping;
-	if (ext3_should_writeback_data(mapping->host)) {
-		/* optimization: no constraints about data */
-skip:
-		return ext3_journal_stop(handle);
-	}
-
-	head = page_buffers(page);
-	blocksize = head->b_size;
-	for (	bh = head, block_start = 0;
-		bh != head || !block_start;
-	    	block_start = block_end, bh = next)
-	{
-		next = bh->b_this_page;
-		block_end = block_start + blocksize;
-		if (block_end <= from)
-			continue;
-		if (block_start >= to) {
-			block_start = to;
-			break;
-		}
-		if (!buffer_mapped(bh))
-		/* prepare_write failed on this bh */
-			break;
-		if (ext3_should_journal_data(mapping->host)) {
-			ret = do_journal_get_write_access(handle, bh);
-			if (ret) {
-				ext3_journal_stop(handle);
-				return ret;
-			}
-		}
-	/*
-	 * block_start here becomes the first block where the current iteration
-	 * of prepare_write failed.
-	 */
-	}
-	if (block_start <= from)
-		goto skip;
-
-	/* commit allocated and zeroed buffers */
-	return mapping->a_ops->commit_write(file, page, from, block_start);
-}
-
 static int ext3_prepare_write(struct file *file, struct page *page,
 			      unsigned from, unsigned to)
 {
 	struct inode *inode = page->mapping->host;
-	int ret, ret2;
-	int needed_blocks = ext3_writepage_trans_blocks(inode);
+	int ret, needed_blocks = ext3_writepage_trans_blocks(inode);
 	handle_t *handle;
 	int retries = 0;
 
 retry:
 	handle = ext3_journal_start(inode, needed_blocks);
-	if (IS_ERR(handle))
-		return PTR_ERR(handle);
+	if (IS_ERR(handle)) {
+		ret = PTR_ERR(handle);
+		goto out;
+	}
 	if (test_opt(inode->i_sb, NOBH) && ext3_should_writeback_data(inode))
 		ret = nobh_prepare_write(page, from, to, ext3_get_block);
 	else
 		ret = block_prepare_write(page, from, to, ext3_get_block);
 	if (ret)
-		goto failure;
+		goto prepare_write_failed;
 
 	if (ext3_should_journal_data(inode)) {
 		ret = walk_page_buffers(handle, page_buffers(page),
 				from, to, NULL, do_journal_get_write_access);
-		if (ret)
-			/* fatal error, just put the handle and return */
-			journal_stop(handle);
 	}
-	return ret;
-
-failure:
-	ret2 = ext3_prepare_failure(file, page, from, to);
-	if (ret2 < 0)
-		return ret2;
+prepare_write_failed:
+	if (ret)
+		ext3_journal_stop(handle);
 	if (ret == -ENOSPC && ext3_should_retry_alloc(inode->i_sb, &retries))
 		goto retry;
-	/* retry number exceeded, or other error like -EDQUOT */
+out:
 	return ret;
 }
 
_

Patches currently in -mm which might be from akpm@...ux-foundation.org are

origin.patch
proc-fix-linkage-with-config_sysctl=y-config_proc_sysctl=n.patch
revert-retries-in-ext3_prepare_write-violate-ordering-requirements.patch
slab-introduce-krealloc-fix.patch
git-acpi.patch
git-alsa.patch
git-alsa-fixup.patch
git-avr32.patch
git-avr32-fixup.patch
git-drm.patch
git-dvb.patch
git-gfs2-nmw.patch
git-ieee1394.patch
git-input.patch
git-kvm.patch
git-libata-all.patch
git-libata-all-ipr-fix.patch
libata-acpi-add-infrastructure-for-drivers-to-use-fix.patch
pata_acpi-restore-driver-fix.patch
revert-rm-pointless-dmaengine-exports.patch
git-md-accel-fix.patch
git-mmc-versus-uevent-use-add_uevent_var-instead-of-open-coding-it.patch
git-ubi.patch
git-netdev-all.patch
vioc-warning-fix.patch
vioc-cast-warning-fix.patch
git-e1000.patch
git-e1000-fixup-2.patch
git-parisc.patch
rm9000-serial-driver.patch
fix-gregkh-pci-pci-piggy-bus.patch
git-pciseg.patch
git-s390.patch
git-unionfs.patch
git-wireless.patch
git-wireless-fixup.patch
fix-x86_64-mm-sched-clock-share.patch
revert-x86_64-mm-change-sysenter_setup-to-__cpuinit-improve-__init-__initdata.patch
x86_64-inhibit-machine-from-asserting-an-nmi-when-doing-alt-sysrq-m-operation-tidy.patch
add-__gfp_movable-for-callers-to-flag-allocations-from-high-memory-that-may-be-migrated-fix.patch
mm-merge-populate-and-nopage-into-fault-fixes-nonlinear-tidy.patch
mm-merge-nopfn-into-fault-fix.patch
i386-use-pte_update_defer-in-ptep_test_and_clear_dirtyyoung-fix.patch
smaps-add-clear_refs-file-to-clear-reference-fix.patch
smaps-add-clear_refs-file-to-clear-reference-fix-fix-2.patch
bias-the-location-of-pages-freed-for-min_free_kbytes-in-the-same-max_order_nr_pages-blocks-tidy.patch
mm-move-common-segment-checks-to-separate-helper-function-v7-tidy.patch
driver_bfin_serial_core-update.patch
uml-driver-formatting-fixes-fix.patch
reduce-size-of-task_struct-on-64-bit-machines.patch
mm-shrink-parent-dentries-when-shrinking-slab.patch
merge-sys_clone-sys_unshare-nsproxy-and-namespace-fix-fix-fix.patch
add-an-anonymous-inode-source-tidy.patch
virtual_eisa_root_init-should-be-__init.patch
proc-maps-protection-fix.patch
proc-maps-protection-tidy.patch
proc-maps-protection-fix-2.patch
fix-cycladesh-for-x86_64-and-probably-others-fix.patch
rtc-add-rtc-rs5c313-driver-tidy.patch
rtc-add-rtc-rs5c313-driver-is-busted.patch
move-die-notifier-handling-to-common-code-fixes-2.patch
move-die-notifier-handling-to-common-code-fix-vmalloc_sync_all.patch
fix-sscanf-%n-match-at-end-of-input-string-tidy.patch
parport-dev-driver-model-support-powerpc-fix.patch
cache-pipe-buf-page-address-for-non-highmem-arch-fix.patch
cache-pipe-buf-page-address-for-non-highmem-arch-fix-tidy.patch
add-support-for-deferrable-timers-respun-tidy.patch
linux-sysdevh-needs-to-include-linux-moduleh.patch
time-smp-friendly-alignment-of-struct-clocksource.patch
move-timekeeping-code-to-timekeepingc-fix.patch
define-and-use-new-eventscpu_lock_acquire-and-cpu_lock_release.patch
call-cpu_chain-with-cpu_down_failed-if-cpu_down_prepare-failed-vs-reduce-size-of-task_struct-on-64-bit-machines.patch
speedup-divides-by-cpu_power-in-scheduler.patch
lutimesat-compat-syscall-and-wire-up-on-x86_64.patch
declare-struct-ktime.patch
make-futex_wait-use-an-hrtimer-for-timeout-fix.patch
sys_futex64-allows-64bit-futexes-workaround.patch
proc-maps-protection-vs-utrace.patch
utrace-prep-2.patch
utrace-vs-reduce-size-of-task_struct-on-64-bit-machines.patch
utrace-printk-borkage.patch
utrace-x86_64-fix.patch
atomich-add-atomic64-cmpxchg-xchg-and-add_unless-to-powerpc.patch
local_t-powerpc-extension.patch
linux-kernel-markers-i386-optimization-fix.patch
revoke-core-code-fix-shared-mapping-revoke.patch
fbdev-hecuba-framebuffer-driver.patch
integrity-new-hooks-fix.patch
integrity-evm-as-an-integrity-service-provider-tidy.patch
integrity-evm-as-an-integrity-service-provider-tidy-fix.patch
integrity-evm-as-an-integrity-service-provider-tidy-fix-2.patch
integrity-ima-integrity_measure-support-tidy.patch
integrity-ima-integrity_measure-support-fix.patch
integrity-ima-integrity_measure-support-fix-2.patch
integrity-tpm-internal-kernel-interface-tidy.patch

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