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writeback: Fix fall-out of initial fix for the infamous slow-umount bug 

Patch fs-explicitly-pass-in-whether-sb-is-pinned-or-not.patch fixed
<https://bugzilla.kernel.org/show_bug.cgi?id=15906> but introduced
some regressions.

Apply fix-ups:
- "writeback: Update dirty flags in two step" fixes behaviour in some
  corner-case
- "writeback: ensure that WB_SYNC_NONE writeback with sb pinned is sync"
  fixes an oops
- "writeback: fix non-integrity write-back" fixes a trivial bug in the
  previous change

Also update fs-explicitly-pass-in-whether-sb-is-pinned-or-not.patch
with the final upstream commit information.

svn path=/dists/trunk/linux-2.6/; revision=15809
This commit is contained in:
Ben Hutchings 2010-05-30 23:23:26 +00:00
parent 226fc7d101
commit b781c01f02
6 changed files with 206 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
debian/changelog vendored
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@ -3,6 +3,10 @@ linux-2.6 (2.6.34-1~experimental.2) UNRELEASED; urgency=low
[ Ben Hutchings ]
* [x86] Reenable rtl8192su, accidentally disabled in previous version
(Closes: #580740)
* writeback: Update dirty flags in two steps
* writeback: ensure that WB_SYNC_NONE writeback with sb pinned is sync
(Closes: #582808)
* writeback: fix non-integrity write-back
[ maximilian attems ]
* topconfig enable CFQ_GROUP_IOSCHED, MFD_WM8994, REGULATOR_MAX8649,

28
debian/patches/bugfix/all/fs-explicitly-pass-in-whether-sb-is-pinned-or-not.patch vendored
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@ -1,13 +1,27 @@
From: Jens Axboe <axboe@kernel.dk>
Date: 2010-05-06 07:08:55
Subject: Explicitly pass in whether sb is pinned or not
From: Jens Axboe <jens.axboe@oracle.com>
Date: Mon, 17 May 2010 12:55:07 +0200
Subject: [PATCH] writeback: fix WB_SYNC_NONE writeback from umount
commit e913fc825dc685a444cb4c1d0f9d32f372f59861 upstream.
Revision two of this patch. I got rid of WB_SYNC_NONE_PIN, since we should not
further muddy the sync type and whether or not the sb is pinned. Instead lets
add a specific flag for this.
When umount calls sync_filesystem(), we first do a WB_SYNC_NONE
writeback to kick off writeback of pending dirty inodes, then follow
that up with a WB_SYNC_ALL to wait for it. Since umount already holds
the sb s_umount mutex, WB_SYNC_NONE ends up doing nothing and all
writeback happens as WB_SYNC_ALL. This can greatly slow down umount,
since WB_SYNC_ALL writeback is a data integrity operation and thus
a bigger hammer than simple WB_SYNC_NONE. For barrier aware file systems
it's a lot slower.
BZ: 15906, Launchpad: 543617
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
[maks: Use earlier version for 2.6.34]
---
fs/fs-writeback.c | 48 +++++++++++++++++++++++++++++++++---------
fs/sync.c | 2 +-
include/linux/backing-dev.h | 2 +-
include/linux/writeback.h | 10 +++++++++
mm/page-writeback.c | 4 +-
5 files changed, 51 insertions(+), 15 deletions(-)
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 4b37f7c..c9ac9cb 100644

57
debian/patches/bugfix/all/writeback-Update-dirty-flags-in-two-steps.patch vendored Normal file
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@ -0,0 +1,57 @@
From: Dmitry Monakhov <dmonakhov@openvz.org>
Date: Fri, 7 May 2010 13:35:44 +0400
Subject: [PATCH 3/5] writeback: Update dirty flags in two steps
commit 5547e8aac6f71505d621a612de2fca0dd988b439 upstream.
Filesystems with delalloc support may dirty inode during writepages.
As result inode will have dirty metadata flags even after write_inode.
In fact we have two dedicated functions for proper data and metadata
writeback. It is reasonable to separate flags updates in two stages.
https://bugzilla.kernel.org/show_bug.cgi?id=15906
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---
fs/fs-writeback.c | 15 +++++++++++----
1 files changed, 11 insertions(+), 4 deletions(-)
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 67db897..0f62957 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -460,11 +460,9 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
BUG_ON(inode->i_state & I_SYNC);
- /* Set I_SYNC, reset I_DIRTY */
- dirty = inode->i_state & I_DIRTY;
+ /* Set I_SYNC, reset I_DIRTY_PAGES */
inode->i_state |= I_SYNC;
- inode->i_state &= ~I_DIRTY;
-
+ inode->i_state &= ~I_DIRTY_PAGES;
spin_unlock(&inode_lock);
ret = do_writepages(mapping, wbc);
@@ -480,6 +478,15 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
ret = err;
}
+ /*
+ * Some filesystems may redirty the inode during the writeback
+ * due to delalloc, clear dirty metadata flags right before
+ * write_inode()
+ */
+ spin_lock(&inode_lock);
+ dirty = inode->i_state & I_DIRTY;
+ inode->i_state &= ~(I_DIRTY_SYNC | I_DIRTY_DATASYNC);
+ spin_unlock(&inode_lock);
/* Don't write the inode if only I_DIRTY_PAGES was set */
if (dirty & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) {
int err = write_inode(inode, wbc);
--
1.7.1

93
debian/patches/bugfix/all/writeback-ensure-WB_SYNC_NONE-writeback-with-sb-pinned-is-sync.patch vendored Normal file
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@ -0,0 +1,93 @@
From: Jens Axboe <jens.axboe@oracle.com>
Date: Tue, 18 May 2010 14:29:29 +0200
Subject: [PATCH 4/5] writeback: ensure that WB_SYNC_NONE writeback with sb pinned is sync
commit 7c8a3554c683f512dbcee26faedb42e4c05f12fa upstream.
Even if the writeout itself isn't a data integrity operation, we need
to ensure that the caller doesn't drop the sb umount sem before we
have actually done the writeback.
This is a fixup for commit e913fc82.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---
fs/fs-writeback.c | 16 +++++++++++-----
1 files changed, 11 insertions(+), 5 deletions(-)
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 0f62957..76f546d 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -193,7 +193,8 @@ static void bdi_wait_on_work_clear(struct bdi_work *work)
}
static void bdi_alloc_queue_work(struct backing_dev_info *bdi,
- struct wb_writeback_args *args)
+ struct wb_writeback_args *args,
+ int wait)
{
struct bdi_work *work;
@@ -205,6 +206,8 @@ static void bdi_alloc_queue_work(struct backing_dev_info *bdi,
if (work) {
bdi_work_init(work, args);
bdi_queue_work(bdi, work);
+ if (wait)
+ bdi_wait_on_work_clear(work);
} else {
struct bdi_writeback *wb = &bdi->wb;
@@ -279,7 +282,7 @@ void bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
args.for_background = 1;
}
- bdi_alloc_queue_work(bdi, &args);
+ bdi_alloc_queue_work(bdi, &args, sb_locked);
}
/*
@@ -909,6 +912,7 @@ long wb_do_writeback(struct bdi_writeback *wb, int force_wait)
while ((work = get_next_work_item(bdi, wb)) != NULL) {
struct wb_writeback_args args = work->args;
+ int post_clear;
/*
* Override sync mode, in case we must wait for completion
@@ -916,11 +920,13 @@ long wb_do_writeback(struct bdi_writeback *wb, int force_wait)
if (force_wait)
work->args.sync_mode = args.sync_mode = WB_SYNC_ALL;
+ post_clear = WB_SYNC_ALL || args.sb_pinned;
+
/*
* If this isn't a data integrity operation, just notify
* that we have seen this work and we are now starting it.
*/
- if (args.sync_mode == WB_SYNC_NONE)
+ if (!post_clear)
wb_clear_pending(wb, work);
wrote += wb_writeback(wb, &args);
@@ -929,7 +935,7 @@ long wb_do_writeback(struct bdi_writeback *wb, int force_wait)
* This is a data integrity writeback, so only do the
* notification when we have completed the work.
*/
- if (args.sync_mode == WB_SYNC_ALL)
+ if (post_clear)
wb_clear_pending(wb, work);
}
@@ -1000,7 +1006,7 @@ static void bdi_writeback_all(struct super_block *sb, long nr_pages)
if (!bdi_has_dirty_io(bdi))
continue;
- bdi_alloc_queue_work(bdi, &args);
+ bdi_alloc_queue_work(bdi, &args, 0);
}
rcu_read_unlock();
--
1.7.1

28
debian/patches/bugfix/all/writeback-fix-non-integrity-write-back.patch vendored Normal file
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@ -0,0 +1,28 @@
From: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Subject: [PATCH] writeback: fix non-integrity write-back
Date: Wed, 26 May 2010 16:08:40 +0300
This is a fix for commit 7c8a3554. Note, I only compile-tested
this.
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
---
fs/fs-writeback.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index ea8592b..0242855 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -920,7 +920,7 @@ long wb_do_writeback(struct bdi_writeback *wb, int force_wait)
if (force_wait)
work->args.sync_mode = args.sync_mode = WB_SYNC_ALL;
- post_clear = WB_SYNC_ALL || args.sb_pinned;
+ post_clear = args.sync_mode == WB_SYNC_ALL || args.sb_pinned;
/*
* If this isn't a data integrity operation, just notify
--
1.6.6.1

3
debian/patches/series/1~experimental.2 vendored
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@ -1 +1,4 @@
- debian/dfsg/drivers-staging-rtl8192su-disable.patch
+ bugfix/all/writeback-Update-dirty-flags-in-two-steps.patch
+ bugfix/all/writeback-ensure-WB_SYNC_NONE-writeback-with-sb-pinned-is-sync.patch
+ bugfix/all/writeback-fix-non-integrity-write-back.patch