EXT4 regression caused 4eec7

EXT4 regression caused 4eec7

[Dmitry Monakhov]

On Sat, 11 May 2013 13:17:38 +0400, Dmitry Monakhov <dmonakhov@openvz.org> wrote:
Non-text part: multipart/mixed
> On Sat, 11 May 2013 12:13:20 +0400, Dmitry Monakhov <dmonakhov@openvz.org> wrote:
> > On Fri, 10 May 2013 15:27:47 -0400, Theodore Ts'o <tytso@mit.edu> wrote:
> > > Hmm, since you seem to be able to reproduce the problem reliably, any
> > > chance you can try bisecting the problem?  I've looked at the commits
> > > that touch fs/jbd2 and nothing is jumping out at me.
> > > 
> > > Also, how many CPU's do you have your system, and what kind of storage
> > > device were you using when you were running iozone (5400rpm HDD,
> > > 7200RPM HDD, RAID array, SSD, etc.)?
> Ok, I've able to reproduce corruption on ext4
> So at this moment we have:
> Slub corruption on XFS testcase: xfstests/generic/013
> Slub corruption on EXT4 testcase: xfstests/generic/299
I've bisected ext4 related issue. It is appeared that it is pure ext4
specific. Regression caused by  following commit
commit 4eec708d263f0ee10861d69251708a225b64cac7
Author: Jan Kara <jack@suse.cz>
Date:   Thu Apr 11 23:56:53 2013 -0400
    ext4: use io_end for multiple bios

TESTCASE: xfstests  generic/299
> 
> In fact both test cases (069'th and 299'th) are just stress tests.
> So this is likely a regression in mm layer. I try to bisect it now.
> 
> 
> #Testcase: xfstests  generic/299
> #DMESG
> ------------[ cut here ]------------
> WARNING: at fs/ext4/inode.c:3223 ext4_ext_direct_IO+0x2cb/0x3c0()
> Modules linked in: cpufreq_ondemand usb_storage acpi_cpufreq freq_table mperf coretemp kvm_intel kvm crc32c_intel ghash_clmulni_intel microcode sg xhci_hcd button sd_mod crc_t10dif aesni_intel ablk_helper cryptd lrw gf128mul glue_helper aes_x86_64 ahci libahci pata_acpi ata_generic dm_mirror dm_region_hash dm_log dm_mod
> CPU: 3 PID: 30537 Comm: fio Not tainted 3.9.0+ #14
> Hardware name:                  /DQ67SW, BIOS SWQ6710H.86A.0052.2011.0520.1802 05/20/2011
>  ffffffff81e44ed6 ffff8801259ffa28 ffffffff818b20ff ffff8801259ffa68
>  ffffffff81060a87 ffff8801259ffa58 ffff880205a921d0 ffff880233192740
>  ffff880176496400 0000000000000000 ffffffffffffffe4 ffff8801259ffa78
> Call Trace:
>  [<ffffffff818b20ff>] dump_stack+0x19/0x22
>  [<ffffffff81060a87>] warn_slowpath_common+0x87/0xb0
>  [<ffffffff81060aca>] warn_slowpath_null+0x1a/0x20
>  [<ffffffff813131eb>] ext4_ext_direct_IO+0x2cb/0x3c0
>  [<ffffffff813161c0>] ? ext4_get_block_write_nolock+0x20/0x20
>  [<ffffffff813132e0>] ? ext4_ext_direct_IO+0x3c0/0x3c0
>  [<ffffffff8131ac9f>] ext4_direct_IO+0x22f/0x3c0
>  [<ffffffff8118db75>] generic_file_direct_write+0x175/0x240
>  [<ffffffff81191bc6>] __generic_file_aio_write+0x556/0x770
>  [<ffffffff8130d2de>] ext4_file_dio_write+0x35e/0x4f0
>  [<ffffffff812929b3>] ? aio_rw_vect_retry+0xc3/0x250
>  [<ffffffff8130d5ae>] ext4_file_write+0x13e/0x190
>  [<ffffffff8130d470>] ? ext4_file_dio_write+0x4f0/0x4f0
>  [<ffffffff812929e3>] aio_rw_vect_retry+0xf3/0x250
>  [<ffffffff811c7f53>] ? might_fault+0x73/0xe0
>  [<ffffffff8130d470>] ? ext4_file_dio_write+0x4f0/0x4f0
>  [<ffffffff812949da>] aio_run_iocb+0x25a/0x3b0
>  [<ffffffff81294e26>] io_submit_one+0x2f6/0x3a0
>  [<ffffffff8129512e>] do_io_submit+0x25e/0x2f0
>  [<ffffffff812926b2>] ? lookup_ioctx+0xc2/0x100
>  [<ffffffff812951d0>] SyS_io_submit+0x10/0x20
>  [<ffffffff818c4ac2>] system_call_fastpath+0x16/0x1b
> ---[ end trace c96126e84d56efc2 ]---
> ------------[ cut here ]------------
> WARNING: at fs/ext4/inode.c:3223 ext4_ext_direct_IO+0x2cb/0x3c0()
> Modules linked in: cpufreq_ondemand usb_storage acpi_cpufreq freq_table mperf coretemp kvm_intel kvm crc32c_intel ghash_clmulni_intel microcode sg xhci_hcd button sd_mod crc_t10dif aesni_intel ablk_helper cryptd lrw gf128mul glue_helper aes_x86_64 ahci libahci pata_acpi ata_generic dm_mirror dm_region_hash dm_log dm_mod
> CPU: 1 PID: 30539 Comm: fio Tainted: G        W    3.9.0+ #14
> Hardware name:                  /DQ67SW, BIOS SWQ6710H.86A.0052.2011.0520.1802 05/20/2011
>  ffffffff81e44ed6 ffff880131209a28 ffffffff818b20ff ffff880131209a68
>  ffffffff81060a87 ffff880131209a58 ffff8801f5347990 ffff88022b9b7e00
>  ffff88023342c508 0000000000000000 ffffffffffffffe4 ffff880131209a78
> Call Trace:
>  [<ffffffff818b20ff>] dump_stack+0x19/0x22
>  [<ffffffff81060a87>] warn_slowpath_common+0x87/0xb0
>  [<ffffffff81060aca>] warn_slowpath_null+0x1a/0x20
>  [<ffffffff813131eb>] ext4_ext_direct_IO+0x2cb/0x3c0
>  [<ffffffff813161c0>] ? ext4_get_block_write_nolock+0x20/0x20
>  [<ffffffff813132e0>] ? ext4_ext_direct_IO+0x3c0/0x3c0
>  [<ffffffff8131ac9f>] ext4_direct_IO+0x22f/0x3c0
>  [<ffffffff8118db75>] generic_file_direct_write+0x175/0x240
>  [<ffffffff81191bc6>] __generic_file_aio_write+0x556/0x770
>  [<ffffffff8130d2de>] ext4_file_dio_write+0x35e/0x4f0
>  [<ffffffff812929b3>] ? aio_rw_vect_retry+0xc3/0x250
>  [<ffffffff8130d5ae>] ext4_file_write+0x13e/0x190
>  [<ffffffff8130d470>] ? ext4_file_dio_write+0x4f0/0x4f0
>  [<ffffffff812929e3>] aio_rw_vect_retry+0xf3/0x250
>  [<ffffffff811c7f53>] ? might_fault+0x73/0xe0
>  [<ffffffff8130d470>] ? ext4_file_dio_write+0x4f0/0x4f0
>  [<ffffffff812949da>] aio_run_iocb+0x25a/0x3b0
>  [<ffffffff81294e26>] io_submit_one+0x2f6/0x3a0
>  [<ffffffff8129512e>] do_io_submit+0x25e/0x2f0
>  [<ffffffff812926b2>] ? lookup_ioctx+0xc2/0x100
>  [<ffffffff812951d0>] SyS_io_submit+0x10/0x20
>  [<ffffffff818c4ac2>] system_call_fastpath+0x16/0x1b
> ---[ end trace c96126e84d56efc3 ]---
> Slab corruption (Tainted: G        W   ): ext4_io_end start=ffff88023342c508, len=64
> Redzone: 0x9f911029d74e35b/0x9f911029d74e35b.
> Last user: [<ffffffff8131fe9b>](ext4_release_io_end+0x12b/0x130)
> 030: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6a 6b 6b a5  kkkkkkkkkkkkjkk.
> Prev obj: start=ffff88023342c4b0, len=64
> Redzone: 0xd84156c5635688c0/0xd84156c5635688c0.
> Last user: [<ffffffff813200d3>](ext4_init_io_end+0x23/0x60)
> 000: 58 cf 42 33 02 88 ff ff c8 27 33 62 01 88 ff ff  X.B3.....'3b....
> 010: d0 51 a4 30 02 88 ff ff 05 00 00 00 00 00 00 00  .Q.0............
> Next obj: start=ffff88023342c560, len=64
> Redzone: 0xd84156c5635688c0/0xd84156c5635688c0.
> Last user: [<ffffffff813200d3>](ext4_init_io_end+0x23/0x60)
> 000: a8 d3 1e 27 02 88 ff ff a0 8d 47 2b 02 88 ff ff  ...'......G+....
> 010: d0 51 a4 30 02 88 ff ff 05 00 00 00 00 00 00 00  .Q.0............
> Slab corruption (Tainted: G        W   ): ext4_io_end start=ffff880176496400, len=64
> Redzone: 0x9f911029d74e35b/0x9f911029d74e35b.
> Last user: [<ffffffff8131fe9b>](ext4_release_io_end+0x12b/0x130)
> 030: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6a 6b 6b a5  kkkkkkkkkkkkjkk.
> Prev obj: start=ffff8801764963a8, len=64
> Redzone: 0xd84156c5635688c0/0xd84156c5635688c0.
> Last user: [<ffffffff813200d3>](ext4_init_io_end+0x23/0x60)
> 000: a8 63 49 76 01 88 ff ff a8 63 49 76 01 88 ff ff  .cIv.....cIv....
> 010: 90 b9 79 2b 02 88 ff ff 00 00 00 00 00 00 00 00  ..y+............
> Next obj: start=ffff880176496458, len=64
> Redzone: 0x9f911029d74e35b/0x9f911029d74e35b.
> Last user: [<ffffffff8131fe9b------------[ cut here ]------------
> 
> 
> > XFS TOO....
> > It it definitely just an ext3/4 related issue.
> > I've run xfstests on xfs and almost immediately have got slub corruption
> > I use following HEAD: 2dbd3cac87250a0d44e07acc86c4224a08522709
> > 
> > 2013-05-11 11:59:30 Slab corruption (Not tainted): xfs_efi_item
> > start=ffff8802335063f0, len=400^M
> > 2013-05-11 11:59:30 Redzone: 0x9f911029d74e35b/0x9f911029d74e35b.^M
> > 2013-05-11 11:59:30 Last user:
> > [<ffffffffa03ba36f>](xfs_efi_item_free+0x3f/0x50 [xfs])^M
> > 2013-05-11 11:59:30 070: 6a 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b
> > jkkkkkkkkkkkkkkk^M
> > 2013-05-11 11:59:30 Single bit error detected. Probably bad RAM.^M
> > 2013-05-11 11:59:30 Run memtest86+ or a similar memory test tool.^M
> > 2013-05-11 11:59:30 Prev obj: start=ffff880233506248, len=400^M
> > 2013-05-11 11:59:30 Redzone: 0xd84156c5635688c0/0xd84156c5635688c0.^M
> > 2013-05-11 11:59:30 Last user:
> > [<ffffffffa034d7bb>](kmem_zone_alloc+0xbb/0x190 [xfs])^M
> > 2013-05-11 11:59:30 000: 48 62 50 33 02 88 ff ff 48 62 50 33 02 88 ff ff
> > HbP3....HbP3....^M
> > 2013-05-11 11:59:30 010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> > ................^M
> > 2013-05-11 11:59:30 Next obj: start=ffff880233506598, len=400^M
> > 2013-05-11 11:59:30 Redzone: 0x9f911029d74e35b/0x9f911029d74e35b.^M
> > > 
> > > Thanks,
> > > 
> > > 						- Ted
> > > --
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> > --
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Re: EXT4 regression caused 4eec7

[Theodore Ts'o]

On Sat, May 11, 2013 at 03:00:53PM +0400, Dmitry Monakhov wrote:
> I've bisected ext4 related issue. It is appeared that it is pure ext4
> specific. Regression caused by  following commit
> commit 4eec708d263f0ee10861d69251708a225b64cac7
> Author: Jan Kara <jack@suse.cz>
> Date:   Thu Apr 11 23:56:53 2013 -0400
>     ext4: use io_end for multiple bios

Hmm... the next question is why did I see this in my testing.  Did you
find this on ia64, or x86?  Also what about the slab corruption which
you saw when running XFS; was that unrelated?

Since at this point it's safer to rollback the change and we can
investigate more deeply how to fix it correctly for the next
development cycle, this is the patch which I'm testing.

	    	   	       	     - Ted

>From dfd5057908a66b414d5d5fa2fc7ff7945e5a277c Mon Sep 17 00:00:00 2001
From: Theodore Ts'o <tytso@mit.edu>
Date: Sat, 11 May 2013 18:59:39 -0400
Subject: [PATCH] Revert "ext4: use io_end for multiple bios"

This reverts commit 4eec708d263f0ee10861d69251708a225b64cac7.

Multiple users have reported crashes which is apparently caused by
this commit.  Thanks to Dmitry Monakhov for bisecting it.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: Dmitry Monakhov <dmonakhov@openvz.org>
Cc: Jan Kara <jack@suse.cz>
---
 fs/ext4/ext4.h    |   8 +---
 fs/ext4/inode.c   |  85 +++++++++++++++++---------------------
 fs/ext4/page-io.c | 121 ++++++++++++++++++++----------------------------------
 3 files changed, 85 insertions(+), 129 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 0aabb34..5aae3d1 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -209,7 +209,6 @@ typedef struct ext4_io_end {
 	ssize_t			size;		/* size of the extent */
 	struct kiocb		*iocb;		/* iocb struct for AIO */
 	int			result;		/* error value for AIO */
-	atomic_t		count;		/* reference counter */
 } ext4_io_end_t;
 
 struct ext4_io_submit {
@@ -2651,14 +2650,11 @@ extern int ext4_move_extents(struct file *o_filp, struct file *d_filp,
 
 /* page-io.c */
 extern int __init ext4_init_pageio(void);
+extern void ext4_add_complete_io(ext4_io_end_t *io_end);
 extern void ext4_exit_pageio(void);
 extern void ext4_ioend_shutdown(struct inode *);
+extern void ext4_free_io_end(ext4_io_end_t *io);
 extern ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags);
-extern ext4_io_end_t *ext4_get_io_end(ext4_io_end_t *io_end);
-extern int ext4_put_io_end(ext4_io_end_t *io_end);
-extern void ext4_put_io_end_defer(ext4_io_end_t *io_end);
-extern void ext4_io_submit_init(struct ext4_io_submit *io,
-				struct writeback_control *wbc);
 extern void ext4_end_io_work(struct work_struct *work);
 extern void ext4_io_submit(struct ext4_io_submit *io);
 extern int ext4_bio_write_page(struct ext4_io_submit *io,
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 793d44b..d666569 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1487,10 +1487,7 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd,
 	struct ext4_io_submit io_submit;
 
 	BUG_ON(mpd->next_page <= mpd->first_page);
-	ext4_io_submit_init(&io_submit, mpd->wbc);
-	io_submit.io_end = ext4_init_io_end(inode, GFP_NOFS);
-	if (!io_submit.io_end)
-		return -ENOMEM;
+	memset(&io_submit, 0, sizeof(io_submit));
 	/*
 	 * We need to start from the first_page to the next_page - 1
 	 * to make sure we also write the mapped dirty buffer_heads.
@@ -1578,8 +1575,6 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd,
 		pagevec_release(&pvec);
 	}
 	ext4_io_submit(&io_submit);
-	/* Drop io_end reference we got from init */
-	ext4_put_io_end_defer(io_submit.io_end);
 	return ret;
 }
 
@@ -2238,16 +2233,9 @@ static int ext4_writepage(struct page *page,
 		 */
 		return __ext4_journalled_writepage(page, len);
 
-	ext4_io_submit_init(&io_submit, wbc);
-	io_submit.io_end = ext4_init_io_end(inode, GFP_NOFS);
-	if (!io_submit.io_end) {
-		redirty_page_for_writepage(wbc, page);
-		return -ENOMEM;
-	}
+	memset(&io_submit, 0, sizeof(io_submit));
 	ret = ext4_bio_write_page(&io_submit, page, len, wbc);
 	ext4_io_submit(&io_submit);
-	/* Drop io_end reference we got from init */
-	ext4_put_io_end_defer(io_submit.io_end);
 	return ret;
 }
 
@@ -3078,13 +3066,9 @@ static void ext4_end_io_dio(struct kiocb *iocb, loff_t offset,
 	struct inode *inode = file_inode(iocb->ki_filp);
         ext4_io_end_t *io_end = iocb->private;
 
-	/* if not async direct IO just return */
-	if (!io_end) {
-		inode_dio_done(inode);
-		if (is_async)
-			aio_complete(iocb, ret, 0);
-		return;
-	}
+	/* if not async direct IO or dio with 0 bytes write, just return */
+	if (!io_end || !size)
+		goto out;
 
 	ext_debug("ext4_end_io_dio(): io_end 0x%p "
 		  "for inode %lu, iocb 0x%p, offset %llu, size %zd\n",
@@ -3092,13 +3076,25 @@ static void ext4_end_io_dio(struct kiocb *iocb, loff_t offset,
 		  size);
 
 	iocb->private = NULL;
+
+	/* if not aio dio with unwritten extents, just free io and return */
+	if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) {
+		ext4_free_io_end(io_end);
+out:
+		inode_dio_done(inode);
+		if (is_async)
+			aio_complete(iocb, ret, 0);
+		return;
+	}
+
 	io_end->offset = offset;
 	io_end->size = size;
 	if (is_async) {
 		io_end->iocb = iocb;
 		io_end->result = ret;
 	}
-	ext4_put_io_end_defer(io_end);
+
+	ext4_add_complete_io(io_end);
 }
 
 /*
@@ -3132,7 +3128,6 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
 	get_block_t *get_block_func = NULL;
 	int dio_flags = 0;
 	loff_t final_size = offset + count;
-	ext4_io_end_t *io_end = NULL;
 
 	/* Use the old path for reads and writes beyond i_size. */
 	if (rw != WRITE || final_size > inode->i_size)
@@ -3171,16 +3166,13 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
 	iocb->private = NULL;
 	ext4_inode_aio_set(inode, NULL);
 	if (!is_sync_kiocb(iocb)) {
-		io_end = ext4_init_io_end(inode, GFP_NOFS);
+		ext4_io_end_t *io_end = ext4_init_io_end(inode, GFP_NOFS);
 		if (!io_end) {
 			ret = -ENOMEM;
 			goto retake_lock;
 		}
 		io_end->flag |= EXT4_IO_END_DIRECT;
-		/*
-		 * Grab reference for DIO. Will be dropped in ext4_end_io_dio()
-		 */
-		iocb->private = ext4_get_io_end(io_end);
+		iocb->private = io_end;
 		/*
 		 * we save the io structure for current async direct
 		 * IO, so that later ext4_map_blocks() could flag the
@@ -3204,27 +3196,26 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
 				   NULL,
 				   dio_flags);
 
+	if (iocb->private)
+		ext4_inode_aio_set(inode, NULL);
 	/*
-	 * Put our reference to io_end. This can free the io_end structure e.g.
-	 * in sync IO case or in case of error. It can even perform extent
-	 * conversion if all bios we submitted finished before we got here.
-	 * Note that in that case iocb->private can be already set to NULL
-	 * here.
+	 * The io_end structure takes a reference to the inode, that
+	 * structure needs to be destroyed and the reference to the
+	 * inode need to be dropped, when IO is complete, even with 0
+	 * byte write, or failed.
+	 *
+	 * In the successful AIO DIO case, the io_end structure will
+	 * be destroyed and the reference to the inode will be dropped
+	 * after the end_io call back function is called.
+	 *
+	 * In the case there is 0 byte write, or error case, since VFS
+	 * direct IO won't invoke the end_io call back function, we
+	 * need to free the end_io structure here.
 	 */
-	if (io_end) {
-		ext4_inode_aio_set(inode, NULL);
-		ext4_put_io_end(io_end);
-		/*
-		 * In case of error or no write ext4_end_io_dio() was not
-		 * called so we have to put iocb's reference.
-		 */
-		if (ret <= 0 && ret != -EIOCBQUEUED) {
-			WARN_ON(iocb->private != io_end);
-			ext4_put_io_end(io_end);
-			iocb->private = NULL;
-		}
-	}
-	if (ret > 0 && !overwrite && ext4_test_inode_state(inode,
+	if (ret != -EIOCBQUEUED && ret <= 0 && iocb->private) {
+		ext4_free_io_end(iocb->private);
+		iocb->private = NULL;
+	} else if (ret > 0 && !overwrite && ext4_test_inode_state(inode,
 						EXT4_STATE_DIO_UNWRITTEN)) {
 		int err;
 		/*
diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index 5929cd0..6626aba 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -61,28 +61,15 @@ void ext4_ioend_shutdown(struct inode *inode)
 		cancel_work_sync(&EXT4_I(inode)->i_unwritten_work);
 }
 
-static void ext4_release_io_end(ext4_io_end_t *io_end)
+void ext4_free_io_end(ext4_io_end_t *io)
 {
-	BUG_ON(!list_empty(&io_end->list));
-	BUG_ON(io_end->flag & EXT4_IO_END_UNWRITTEN);
-
-	if (atomic_dec_and_test(&EXT4_I(io_end->inode)->i_ioend_count))
-		wake_up_all(ext4_ioend_wq(io_end->inode));
-	if (io_end->flag & EXT4_IO_END_DIRECT)
-		inode_dio_done(io_end->inode);
-	if (io_end->iocb)
-		aio_complete(io_end->iocb, io_end->result, 0);
-	kmem_cache_free(io_end_cachep, io_end);
-}
-
-static void ext4_clear_io_unwritten_flag(ext4_io_end_t *io_end)
-{
-	struct inode *inode = io_end->inode;
+	BUG_ON(!io);
+	BUG_ON(!list_empty(&io->list));
+	BUG_ON(io->flag & EXT4_IO_END_UNWRITTEN);
 
-	io_end->flag &= ~EXT4_IO_END_UNWRITTEN;
-	/* Wake up anyone waiting on unwritten extent conversion */
-	if (atomic_dec_and_test(&EXT4_I(inode)->i_unwritten))
-		wake_up_all(ext4_ioend_wq(inode));
+	if (atomic_dec_and_test(&EXT4_I(io->inode)->i_ioend_count))
+		wake_up_all(ext4_ioend_wq(io->inode));
+	kmem_cache_free(io_end_cachep, io);
 }
 
 /* check a range of space and convert unwritten extents to written. */
@@ -105,8 +92,13 @@ static int ext4_end_io(ext4_io_end_t *io)
 			 "(inode %lu, offset %llu, size %zd, error %d)",
 			 inode->i_ino, offset, size, ret);
 	}
-	ext4_clear_io_unwritten_flag(io);
-	ext4_release_io_end(io);
+	/* Wake up anyone waiting on unwritten extent conversion */
+	if (atomic_dec_and_test(&EXT4_I(inode)->i_unwritten))
+		wake_up_all(ext4_ioend_wq(inode));
+	if (io->flag & EXT4_IO_END_DIRECT)
+		inode_dio_done(inode);
+	if (io->iocb)
+		aio_complete(io->iocb, io->result, 0);
 	return ret;
 }
 
@@ -137,7 +129,7 @@ static void dump_completed_IO(struct inode *inode)
 }
 
 /* Add the io_end to per-inode completed end_io list. */
-static void ext4_add_complete_io(ext4_io_end_t *io_end)
+void ext4_add_complete_io(ext4_io_end_t *io_end)
 {
 	struct ext4_inode_info *ei = EXT4_I(io_end->inode);
 	struct workqueue_struct *wq;
@@ -174,6 +166,8 @@ static int ext4_do_flush_completed_IO(struct inode *inode)
 		err = ext4_end_io(io);
 		if (unlikely(!ret && err))
 			ret = err;
+		io->flag &= ~EXT4_IO_END_UNWRITTEN;
+		ext4_free_io_end(io);
 	}
 	return ret;
 }
@@ -205,43 +199,10 @@ ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags)
 		atomic_inc(&EXT4_I(inode)->i_ioend_count);
 		io->inode = inode;
 		INIT_LIST_HEAD(&io->list);
-		atomic_set(&io->count, 1);
 	}
 	return io;
 }
 
-void ext4_put_io_end_defer(ext4_io_end_t *io_end)
-{
-	if (atomic_dec_and_test(&io_end->count)) {
-		if (!(io_end->flag & EXT4_IO_END_UNWRITTEN) || !io_end->size) {
-			ext4_release_io_end(io_end);
-			return;
-		}
-		ext4_add_complete_io(io_end);
-	}
-}
-
-int ext4_put_io_end(ext4_io_end_t *io_end)
-{
-	int err = 0;
-
-	if (atomic_dec_and_test(&io_end->count)) {
-		if (io_end->flag & EXT4_IO_END_UNWRITTEN) {
-			err = ext4_convert_unwritten_extents(io_end->inode,
-						io_end->offset, io_end->size);
-			ext4_clear_io_unwritten_flag(io_end);
-		}
-		ext4_release_io_end(io_end);
-	}
-	return err;
-}
-
-ext4_io_end_t *ext4_get_io_end(ext4_io_end_t *io_end)
-{
-	atomic_inc(&io_end->count);
-	return io_end;
-}
-
 /*
  * Print an buffer I/O error compatible with the fs/buffer.c.  This
  * provides compatibility with dmesg scrapers that look for a specific
@@ -324,7 +285,12 @@ static void ext4_end_bio(struct bio *bio, int error)
 			     bi_sector >> (inode->i_blkbits - 9));
 	}
 
-	ext4_put_io_end_defer(io_end);
+	if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) {
+		ext4_free_io_end(io_end);
+		return;
+	}
+
+	ext4_add_complete_io(io_end);
 }
 
 void ext4_io_submit(struct ext4_io_submit *io)
@@ -338,37 +304,40 @@ void ext4_io_submit(struct ext4_io_submit *io)
 		bio_put(io->io_bio);
 	}
 	io->io_bio = NULL;
-}
-
-void ext4_io_submit_init(struct ext4_io_submit *io,
-			 struct writeback_control *wbc)
-{
-	io->io_op = (wbc->sync_mode == WB_SYNC_ALL ?  WRITE_SYNC : WRITE);
-	io->io_bio = NULL;
+	io->io_op = 0;
 	io->io_end = NULL;
 }
 
-static int io_submit_init_bio(struct ext4_io_submit *io,
-			      struct buffer_head *bh)
+static int io_submit_init(struct ext4_io_submit *io,
+			  struct inode *inode,
+			  struct writeback_control *wbc,
+			  struct buffer_head *bh)
 {
+	ext4_io_end_t *io_end;
+	struct page *page = bh->b_page;
 	int nvecs = bio_get_nr_vecs(bh->b_bdev);
 	struct bio *bio;
 
+	io_end = ext4_init_io_end(inode, GFP_NOFS);
+	if (!io_end)
+		return -ENOMEM;
 	bio = bio_alloc(GFP_NOIO, min(nvecs, BIO_MAX_PAGES));
 	bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9);
 	bio->bi_bdev = bh->b_bdev;
+	bio->bi_private = io->io_end = io_end;
 	bio->bi_end_io = ext4_end_bio;
-	bio->bi_private = ext4_get_io_end(io->io_end);
-	if (!io->io_end->size)
-		io->io_end->offset = (bh->b_page->index << PAGE_CACHE_SHIFT)
-				     + bh_offset(bh);
+
+	io_end->offset = (page->index << PAGE_CACHE_SHIFT) + bh_offset(bh);
+
 	io->io_bio = bio;
+	io->io_op = (wbc->sync_mode == WB_SYNC_ALL ?  WRITE_SYNC : WRITE);
 	io->io_next_block = bh->b_blocknr;
 	return 0;
 }
 
 static int io_submit_add_bh(struct ext4_io_submit *io,
 			    struct inode *inode,
+			    struct writeback_control *wbc,
 			    struct buffer_head *bh)
 {
 	ext4_io_end_t *io_end;
@@ -379,18 +348,18 @@ submit_and_retry:
 		ext4_io_submit(io);
 	}
 	if (io->io_bio == NULL) {
-		ret = io_submit_init_bio(io, bh);
+		ret = io_submit_init(io, inode, wbc, bh);
 		if (ret)
 			return ret;
 	}
-	ret = bio_add_page(io->io_bio, bh->b_page, bh->b_size, bh_offset(bh));
-	if (ret != bh->b_size)
-		goto submit_and_retry;
 	io_end = io->io_end;
 	if (test_clear_buffer_uninit(bh))
 		ext4_set_io_unwritten_flag(inode, io_end);
-	io_end->size += bh->b_size;
+	io->io_end->size += bh->b_size;
 	io->io_next_block++;
+	ret = bio_add_page(io->io_bio, bh->b_page, bh->b_size, bh_offset(bh));
+	if (ret != bh->b_size)
+		goto submit_and_retry;
 	return 0;
 }
 
@@ -462,7 +431,7 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
 	do {
 		if (!buffer_async_write(bh))
 			continue;
-		ret = io_submit_add_bh(io, inode, bh);
+		ret = io_submit_add_bh(io, inode, wbc, bh);
 		if (ret) {
 			/*
 			 * We only get here on ENOMEM.  Not much else
-- 
1.7.12.rc0.22.gcdd159b

Re: EXT4 regression caused 4eec7

[Dmitry Monakhov]

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On Sat, 11 May 2013 19:05:59 -0400, Theodore Ts'o <tytso@mit.edu> wrote:
> On Sat, May 11, 2013 at 03:00:53PM +0400, Dmitry Monakhov wrote:
> > I've bisected ext4 related issue. It is appeared that it is pure ext4
> > specific. Regression caused by  following commit
> > commit 4eec708d263f0ee10861d69251708a225b64cac7
> > Author: Jan Kara <jack@suse.cz>
> > Date:   Thu Apr 11 23:56:53 2013 -0400
> >     ext4: use io_end for multiple bios
> 
> Hmm... the next question is why did I see this in my testing.  Did you
> find this on ia64, or x86?
No simple x86_64. 
> Also what about the slab corruption which
> you saw when running XFS; was that unrelated?
My theory about mysterious corruption in mm layer which broke everything
was wrong. We have to absolutely independent regressions in  different
filesystems:
* Slub corruption on XFS
  - testcase: xfstests/generic/007
  - bad commit: 666d64 
  - LINK: https://lkml.org/lkml/2013/5/11/154

* Slub corruption on EXT4
  - testcase: xfstests/generic/299
  - bad commit: 4eec70
  - link: https://lkml.org/lkml/2013/5/11/37
  - fix: https://lkml.org/lkml/2013/5/11/142

In fact '4eec70' are vexing because I have reviewed and tested this patch before
it was marked as Review-by, but missed the bug. This is because xfstests
was executed manually logs was full of warnings but tainted flag was not
checked at the end. To prevent this thing in future I'll always use my
local autotest(http://autotest.github.io/) farm next time.

BTW here is my config with various debug options enabled.

[-- Attachment #2: config.xz --]
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[-- Attachment #3: Type: text/plain, Size: 14960 bytes --]


> 
> Since at this point it's safer to rollback the change and we can
> investigate more deeply how to fix it correctly for the next
> development cycle, this is the patch which I'm testing.
> 
> 	    	   	       	     - Ted
> 
> From dfd5057908a66b414d5d5fa2fc7ff7945e5a277c Mon Sep 17 00:00:00 2001
> From: Theodore Ts'o <tytso@mit.edu>
> Date: Sat, 11 May 2013 18:59:39 -0400
> Subject: [PATCH] Revert "ext4: use io_end for multiple bios"
> 
> This reverts commit 4eec708d263f0ee10861d69251708a225b64cac7.
> 
> Multiple users have reported crashes which is apparently caused by
> this commit.  Thanks to Dmitry Monakhov for bisecting it.
> 
> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
> Cc: Dmitry Monakhov <dmonakhov@openvz.org>
> Cc: Jan Kara <jack@suse.cz>
> ---
>  fs/ext4/ext4.h    |   8 +---
>  fs/ext4/inode.c   |  85 +++++++++++++++++---------------------
>  fs/ext4/page-io.c | 121 ++++++++++++++++++++----------------------------------
>  3 files changed, 85 insertions(+), 129 deletions(-)
> 
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index 0aabb34..5aae3d1 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -209,7 +209,6 @@ typedef struct ext4_io_end {
>  	ssize_t			size;		/* size of the extent */
>  	struct kiocb		*iocb;		/* iocb struct for AIO */
>  	int			result;		/* error value for AIO */
> -	atomic_t		count;		/* reference counter */
>  } ext4_io_end_t;
>  
>  struct ext4_io_submit {
> @@ -2651,14 +2650,11 @@ extern int ext4_move_extents(struct file *o_filp, struct file *d_filp,
>  
>  /* page-io.c */
>  extern int __init ext4_init_pageio(void);
> +extern void ext4_add_complete_io(ext4_io_end_t *io_end);
>  extern void ext4_exit_pageio(void);
>  extern void ext4_ioend_shutdown(struct inode *);
> +extern void ext4_free_io_end(ext4_io_end_t *io);
>  extern ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags);
> -extern ext4_io_end_t *ext4_get_io_end(ext4_io_end_t *io_end);
> -extern int ext4_put_io_end(ext4_io_end_t *io_end);
> -extern void ext4_put_io_end_defer(ext4_io_end_t *io_end);
> -extern void ext4_io_submit_init(struct ext4_io_submit *io,
> -				struct writeback_control *wbc);
>  extern void ext4_end_io_work(struct work_struct *work);
>  extern void ext4_io_submit(struct ext4_io_submit *io);
>  extern int ext4_bio_write_page(struct ext4_io_submit *io,
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 793d44b..d666569 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -1487,10 +1487,7 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd,
>  	struct ext4_io_submit io_submit;
>  
>  	BUG_ON(mpd->next_page <= mpd->first_page);
> -	ext4_io_submit_init(&io_submit, mpd->wbc);
> -	io_submit.io_end = ext4_init_io_end(inode, GFP_NOFS);
> -	if (!io_submit.io_end)
> -		return -ENOMEM;
> +	memset(&io_submit, 0, sizeof(io_submit));
>  	/*
>  	 * We need to start from the first_page to the next_page - 1
>  	 * to make sure we also write the mapped dirty buffer_heads.
> @@ -1578,8 +1575,6 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd,
>  		pagevec_release(&pvec);
>  	}
>  	ext4_io_submit(&io_submit);
> -	/* Drop io_end reference we got from init */
> -	ext4_put_io_end_defer(io_submit.io_end);
>  	return ret;
>  }
>  
> @@ -2238,16 +2233,9 @@ static int ext4_writepage(struct page *page,
>  		 */
>  		return __ext4_journalled_writepage(page, len);
>  
> -	ext4_io_submit_init(&io_submit, wbc);
> -	io_submit.io_end = ext4_init_io_end(inode, GFP_NOFS);
> -	if (!io_submit.io_end) {
> -		redirty_page_for_writepage(wbc, page);
> -		return -ENOMEM;
> -	}
> +	memset(&io_submit, 0, sizeof(io_submit));
>  	ret = ext4_bio_write_page(&io_submit, page, len, wbc);
>  	ext4_io_submit(&io_submit);
> -	/* Drop io_end reference we got from init */
> -	ext4_put_io_end_defer(io_submit.io_end);
>  	return ret;
>  }
>  
> @@ -3078,13 +3066,9 @@ static void ext4_end_io_dio(struct kiocb *iocb, loff_t offset,
>  	struct inode *inode = file_inode(iocb->ki_filp);
>          ext4_io_end_t *io_end = iocb->private;
>  
> -	/* if not async direct IO just return */
> -	if (!io_end) {
> -		inode_dio_done(inode);
> -		if (is_async)
> -			aio_complete(iocb, ret, 0);
> -		return;
> -	}
> +	/* if not async direct IO or dio with 0 bytes write, just return */
> +	if (!io_end || !size)
> +		goto out;
>  
>  	ext_debug("ext4_end_io_dio(): io_end 0x%p "
>  		  "for inode %lu, iocb 0x%p, offset %llu, size %zd\n",
> @@ -3092,13 +3076,25 @@ static void ext4_end_io_dio(struct kiocb *iocb, loff_t offset,
>  		  size);
>  
>  	iocb->private = NULL;
> +
> +	/* if not aio dio with unwritten extents, just free io and return */
> +	if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) {
> +		ext4_free_io_end(io_end);
> +out:
> +		inode_dio_done(inode);
> +		if (is_async)
> +			aio_complete(iocb, ret, 0);
> +		return;
> +	}
> +
>  	io_end->offset = offset;
>  	io_end->size = size;
>  	if (is_async) {
>  		io_end->iocb = iocb;
>  		io_end->result = ret;
>  	}
> -	ext4_put_io_end_defer(io_end);
> +
> +	ext4_add_complete_io(io_end);
>  }
>  
>  /*
> @@ -3132,7 +3128,6 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
>  	get_block_t *get_block_func = NULL;
>  	int dio_flags = 0;
>  	loff_t final_size = offset + count;
> -	ext4_io_end_t *io_end = NULL;
>  
>  	/* Use the old path for reads and writes beyond i_size. */
>  	if (rw != WRITE || final_size > inode->i_size)
> @@ -3171,16 +3166,13 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
>  	iocb->private = NULL;
>  	ext4_inode_aio_set(inode, NULL);
>  	if (!is_sync_kiocb(iocb)) {
> -		io_end = ext4_init_io_end(inode, GFP_NOFS);
> +		ext4_io_end_t *io_end = ext4_init_io_end(inode, GFP_NOFS);
>  		if (!io_end) {
>  			ret = -ENOMEM;
>  			goto retake_lock;
>  		}
>  		io_end->flag |= EXT4_IO_END_DIRECT;
> -		/*
> -		 * Grab reference for DIO. Will be dropped in ext4_end_io_dio()
> -		 */
> -		iocb->private = ext4_get_io_end(io_end);
> +		iocb->private = io_end;
>  		/*
>  		 * we save the io structure for current async direct
>  		 * IO, so that later ext4_map_blocks() could flag the
> @@ -3204,27 +3196,26 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
>  				   NULL,
>  				   dio_flags);
>  
> +	if (iocb->private)
> +		ext4_inode_aio_set(inode, NULL);
>  	/*
> -	 * Put our reference to io_end. This can free the io_end structure e.g.
> -	 * in sync IO case or in case of error. It can even perform extent
> -	 * conversion if all bios we submitted finished before we got here.
> -	 * Note that in that case iocb->private can be already set to NULL
> -	 * here.
> +	 * The io_end structure takes a reference to the inode, that
> +	 * structure needs to be destroyed and the reference to the
> +	 * inode need to be dropped, when IO is complete, even with 0
> +	 * byte write, or failed.
> +	 *
> +	 * In the successful AIO DIO case, the io_end structure will
> +	 * be destroyed and the reference to the inode will be dropped
> +	 * after the end_io call back function is called.
> +	 *
> +	 * In the case there is 0 byte write, or error case, since VFS
> +	 * direct IO won't invoke the end_io call back function, we
> +	 * need to free the end_io structure here.
>  	 */
> -	if (io_end) {
> -		ext4_inode_aio_set(inode, NULL);
> -		ext4_put_io_end(io_end);
> -		/*
> -		 * In case of error or no write ext4_end_io_dio() was not
> -		 * called so we have to put iocb's reference.
> -		 */
> -		if (ret <= 0 && ret != -EIOCBQUEUED) {
> -			WARN_ON(iocb->private != io_end);
> -			ext4_put_io_end(io_end);
> -			iocb->private = NULL;
> -		}
> -	}
> -	if (ret > 0 && !overwrite && ext4_test_inode_state(inode,
> +	if (ret != -EIOCBQUEUED && ret <= 0 && iocb->private) {
> +		ext4_free_io_end(iocb->private);
> +		iocb->private = NULL;
> +	} else if (ret > 0 && !overwrite && ext4_test_inode_state(inode,
>  						EXT4_STATE_DIO_UNWRITTEN)) {
>  		int err;
>  		/*
> diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
> index 5929cd0..6626aba 100644
> --- a/fs/ext4/page-io.c
> +++ b/fs/ext4/page-io.c
> @@ -61,28 +61,15 @@ void ext4_ioend_shutdown(struct inode *inode)
>  		cancel_work_sync(&EXT4_I(inode)->i_unwritten_work);
>  }
>  
> -static void ext4_release_io_end(ext4_io_end_t *io_end)
> +void ext4_free_io_end(ext4_io_end_t *io)
>  {
> -	BUG_ON(!list_empty(&io_end->list));
> -	BUG_ON(io_end->flag & EXT4_IO_END_UNWRITTEN);
> -
> -	if (atomic_dec_and_test(&EXT4_I(io_end->inode)->i_ioend_count))
> -		wake_up_all(ext4_ioend_wq(io_end->inode));
> -	if (io_end->flag & EXT4_IO_END_DIRECT)
> -		inode_dio_done(io_end->inode);
> -	if (io_end->iocb)
> -		aio_complete(io_end->iocb, io_end->result, 0);
> -	kmem_cache_free(io_end_cachep, io_end);
> -}
> -
> -static void ext4_clear_io_unwritten_flag(ext4_io_end_t *io_end)
> -{
> -	struct inode *inode = io_end->inode;
> +	BUG_ON(!io);
> +	BUG_ON(!list_empty(&io->list));
> +	BUG_ON(io->flag & EXT4_IO_END_UNWRITTEN);
>  
> -	io_end->flag &= ~EXT4_IO_END_UNWRITTEN;
> -	/* Wake up anyone waiting on unwritten extent conversion */
> -	if (atomic_dec_and_test(&EXT4_I(inode)->i_unwritten))
> -		wake_up_all(ext4_ioend_wq(inode));
> +	if (atomic_dec_and_test(&EXT4_I(io->inode)->i_ioend_count))
> +		wake_up_all(ext4_ioend_wq(io->inode));
> +	kmem_cache_free(io_end_cachep, io);
>  }
>  
>  /* check a range of space and convert unwritten extents to written. */
> @@ -105,8 +92,13 @@ static int ext4_end_io(ext4_io_end_t *io)
>  			 "(inode %lu, offset %llu, size %zd, error %d)",
>  			 inode->i_ino, offset, size, ret);
>  	}
> -	ext4_clear_io_unwritten_flag(io);
> -	ext4_release_io_end(io);
> +	/* Wake up anyone waiting on unwritten extent conversion */
> +	if (atomic_dec_and_test(&EXT4_I(inode)->i_unwritten))
> +		wake_up_all(ext4_ioend_wq(inode));
> +	if (io->flag & EXT4_IO_END_DIRECT)
> +		inode_dio_done(inode);
> +	if (io->iocb)
> +		aio_complete(io->iocb, io->result, 0);
>  	return ret;
>  }
>  
> @@ -137,7 +129,7 @@ static void dump_completed_IO(struct inode *inode)
>  }
>  
>  /* Add the io_end to per-inode completed end_io list. */
> -static void ext4_add_complete_io(ext4_io_end_t *io_end)
> +void ext4_add_complete_io(ext4_io_end_t *io_end)
>  {
>  	struct ext4_inode_info *ei = EXT4_I(io_end->inode);
>  	struct workqueue_struct *wq;
> @@ -174,6 +166,8 @@ static int ext4_do_flush_completed_IO(struct inode *inode)
>  		err = ext4_end_io(io);
>  		if (unlikely(!ret && err))
>  			ret = err;
> +		io->flag &= ~EXT4_IO_END_UNWRITTEN;
> +		ext4_free_io_end(io);
>  	}
>  	return ret;
>  }
> @@ -205,43 +199,10 @@ ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags)
>  		atomic_inc(&EXT4_I(inode)->i_ioend_count);
>  		io->inode = inode;
>  		INIT_LIST_HEAD(&io->list);
> -		atomic_set(&io->count, 1);
>  	}
>  	return io;
>  }
>  
> -void ext4_put_io_end_defer(ext4_io_end_t *io_end)
> -{
> -	if (atomic_dec_and_test(&io_end->count)) {
> -		if (!(io_end->flag & EXT4_IO_END_UNWRITTEN) || !io_end->size) {
> -			ext4_release_io_end(io_end);
> -			return;
> -		}
> -		ext4_add_complete_io(io_end);
> -	}
> -}
> -
> -int ext4_put_io_end(ext4_io_end_t *io_end)
> -{
> -	int err = 0;
> -
> -	if (atomic_dec_and_test(&io_end->count)) {
> -		if (io_end->flag & EXT4_IO_END_UNWRITTEN) {
> -			err = ext4_convert_unwritten_extents(io_end->inode,
> -						io_end->offset, io_end->size);
> -			ext4_clear_io_unwritten_flag(io_end);
> -		}
> -		ext4_release_io_end(io_end);
> -	}
> -	return err;
> -}
> -
> -ext4_io_end_t *ext4_get_io_end(ext4_io_end_t *io_end)
> -{
> -	atomic_inc(&io_end->count);
> -	return io_end;
> -}
> -
>  /*
>   * Print an buffer I/O error compatible with the fs/buffer.c.  This
>   * provides compatibility with dmesg scrapers that look for a specific
> @@ -324,7 +285,12 @@ static void ext4_end_bio(struct bio *bio, int error)
>  			     bi_sector >> (inode->i_blkbits - 9));
>  	}
>  
> -	ext4_put_io_end_defer(io_end);
> +	if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) {
> +		ext4_free_io_end(io_end);
> +		return;
> +	}
> +
> +	ext4_add_complete_io(io_end);
>  }
>  
>  void ext4_io_submit(struct ext4_io_submit *io)
> @@ -338,37 +304,40 @@ void ext4_io_submit(struct ext4_io_submit *io)
>  		bio_put(io->io_bio);
>  	}
>  	io->io_bio = NULL;
> -}
> -
> -void ext4_io_submit_init(struct ext4_io_submit *io,
> -			 struct writeback_control *wbc)
> -{
> -	io->io_op = (wbc->sync_mode == WB_SYNC_ALL ?  WRITE_SYNC : WRITE);
> -	io->io_bio = NULL;
> +	io->io_op = 0;
>  	io->io_end = NULL;
>  }
>  
> -static int io_submit_init_bio(struct ext4_io_submit *io,
> -			      struct buffer_head *bh)
> +static int io_submit_init(struct ext4_io_submit *io,
> +			  struct inode *inode,
> +			  struct writeback_control *wbc,
> +			  struct buffer_head *bh)
>  {
> +	ext4_io_end_t *io_end;
> +	struct page *page = bh->b_page;
>  	int nvecs = bio_get_nr_vecs(bh->b_bdev);
>  	struct bio *bio;
>  
> +	io_end = ext4_init_io_end(inode, GFP_NOFS);
> +	if (!io_end)
> +		return -ENOMEM;
>  	bio = bio_alloc(GFP_NOIO, min(nvecs, BIO_MAX_PAGES));
>  	bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9);
>  	bio->bi_bdev = bh->b_bdev;
> +	bio->bi_private = io->io_end = io_end;
>  	bio->bi_end_io = ext4_end_bio;
> -	bio->bi_private = ext4_get_io_end(io->io_end);
> -	if (!io->io_end->size)
> -		io->io_end->offset = (bh->b_page->index << PAGE_CACHE_SHIFT)
> -				     + bh_offset(bh);
> +
> +	io_end->offset = (page->index << PAGE_CACHE_SHIFT) + bh_offset(bh);
> +
>  	io->io_bio = bio;
> +	io->io_op = (wbc->sync_mode == WB_SYNC_ALL ?  WRITE_SYNC : WRITE);
>  	io->io_next_block = bh->b_blocknr;
>  	return 0;
>  }
>  
>  static int io_submit_add_bh(struct ext4_io_submit *io,
>  			    struct inode *inode,
> +			    struct writeback_control *wbc,
>  			    struct buffer_head *bh)
>  {
>  	ext4_io_end_t *io_end;
> @@ -379,18 +348,18 @@ submit_and_retry:
>  		ext4_io_submit(io);
>  	}
>  	if (io->io_bio == NULL) {
> -		ret = io_submit_init_bio(io, bh);
> +		ret = io_submit_init(io, inode, wbc, bh);
>  		if (ret)
>  			return ret;
>  	}
> -	ret = bio_add_page(io->io_bio, bh->b_page, bh->b_size, bh_offset(bh));
> -	if (ret != bh->b_size)
> -		goto submit_and_retry;
>  	io_end = io->io_end;
>  	if (test_clear_buffer_uninit(bh))
>  		ext4_set_io_unwritten_flag(inode, io_end);
> -	io_end->size += bh->b_size;
> +	io->io_end->size += bh->b_size;
>  	io->io_next_block++;
> +	ret = bio_add_page(io->io_bio, bh->b_page, bh->b_size, bh_offset(bh));
> +	if (ret != bh->b_size)
> +		goto submit_and_retry;
>  	return 0;
>  }
>  
> @@ -462,7 +431,7 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
>  	do {
>  		if (!buffer_async_write(bh))
>  			continue;
> -		ret = io_submit_add_bh(io, inode, bh);
> +		ret = io_submit_add_bh(io, inode, wbc, bh);
>  		if (ret) {
>  			/*
>  			 * We only get here on ENOMEM.  Not much else
> -- 
> 1.7.12.rc0.22.gcdd159b
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: Re: Re: EXT4 regression caused 4eec7

[EUNBONG SONG]

>> Since at this point it's safer to rollback the change and we can
>> investigate more deeply how to fix it correctly for the next
>> development cycle, this is the patch which I'm testing.

>>                     - Ted

> Hello, I've tested with your patch. But the same problem was reproduced.
> Currently, I'm trying to git bisect. If i done git bisect, i will let you know.

Hi, I've done git bisect. and panic at jbd2_journal_put_journal_head() is caused by 
ae4647fb7654676fc44a97e86eb35f9f06b99f66: "jbd2: reduce journal_head size."
I write just code patch which revert ae4647fb7654676fc44a97e86eb35f9f06b99f66 because
I don't know the root cause. 


Signed-off-by: Eunbong Song <eunb.song@samsung.com>
---
 include/linux/journal-head.h |   11 +++++++++--
 1 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/include/linux/journal-head.h b/include/linux/journal-head.h
index 13a3da2..c18b46f 100644
--- a/include/linux/journal-head.h
+++ b/include/linux/journal-head.h
@@ -31,14 +31,21 @@ struct journal_head {
 	/*
 	 * Journalling list for this buffer [jbd_lock_bh_state()]
 	 */
-	unsigned b_jlist:4;
+	unsigned b_jlist;
 
 	/*
 	 * This flag signals the buffer has been modified by
 	 * the currently running transaction
 	 * [jbd_lock_bh_state()]
 	 */
-	unsigned b_modified:1;
+	unsigned b_modified;
+
+	/*
+	 * This feild tracks the last transaction id in which this buffer
+	 * has been cowed
+	 * [jbd_lock_bh_state()]
+	 */
+	tid_t b_cow_tid;
 
 	/*
 	 * Copy of the buffer data frozen for writing to the log.
-- 
1.7.0.4


Thanks. 

Re: Re: Re: EXT4 regression caused 4eec7

[Dmitry Monakhov]

On Sun, 12 May 2013 13:05:00 +0000 (GMT), EUNBONG SONG <eunb.song@samsung.com> wrote:
> 
> 
> >> Since at this point it's safer to rollback the change and we can
> >> investigate more deeply how to fix it correctly for the next
> >> development cycle, this is the patch which I'm testing.
> 
> >>                     - Ted
> 
> > Hello, I've tested with your patch. But the same problem was reproduced.
> > Currently, I'm trying to git bisect. If i done git bisect, i will let you know.
> 
> Hi, I've done git bisect. and panic at jbd2_journal_put_journal_head() is caused by 
> ae4647fb7654676fc44a97e86eb35f9f06b99f66: "jbd2: reduce journal_head size."
OK that explains both regressions ext4/jbd2 and ext3/jbd(https://lkml.org/lkml/2013/5/10/434)
Probably some race because b_jlist accessed w/o lock some places. 
BUT i still can not reproduce original issue :(
I've tried all types of disks near me (ssd,hdd,usb-dongle),
What disk type you use? Is it reproducible on x86?
Please post following info:
#fdisk -l  $HDD
#hdparm -t $HDD
#df -h 
#cat /proc/mounts

> I write just code patch which revert ae4647fb7654676fc44a97e86eb35f9f06b99f66 because
> I don't know the root cause. 
> 
> 
> Signed-off-by: Eunbong Song <eunb.song@samsung.com>
> ---
>  include/linux/journal-head.h |   11 +++++++++--
>  1 files changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/journal-head.h b/include/linux/journal-head.h
> index 13a3da2..c18b46f 100644
> --- a/include/linux/journal-head.h
> +++ b/include/linux/journal-head.h
> @@ -31,14 +31,21 @@ struct journal_head {
>  	/*
>  	 * Journalling list for this buffer [jbd_lock_bh_state()]
>  	 */
> -	unsigned b_jlist:4;
> +	unsigned b_jlist;
>  
>  	/*
>  	 * This flag signals the buffer has been modified by
>  	 * the currently running transaction
>  	 * [jbd_lock_bh_state()]
>  	 */
> -	unsigned b_modified:1;
> +	unsigned b_modified;
> +
> +	/*
> +	 * This feild tracks the last transaction id in which this buffer
> +	 * has been cowed
> +	 * [jbd_lock_bh_state()]
> +	 */
> +	tid_t b_cow_tid;
>  
>  	/*
>  	 * Copy of the buffer data frozen for writing to the log.
> -- 
> 1.7.0.4
> 
> 
> Thanks. N‹㎠咽r›y鉉šbXФ푤v^–)頻{.n+‰램Š{‘喩zX㎍›●}ž꼿z&j:+v‰㉭\a‘喩zZ+€+zf＂hšˆ~††i鎬zwⅱ?™②&)刪f”^j푹ym…@Aa뛴\x7f\f0띠h’i\x7f

Re: Re: Re: EXT4 regression caused 4eec7

[Jan Kara]

On Sun 12-05-13 13:04:59, EUNBONG SONG wrote:
> 
> 
> >> Since at this point it's safer to rollback the change and we can
> >> investigate more deeply how to fix it correctly for the next
> >> development cycle, this is the patch which I'm testing.
> 
> >>                     - Ted
> 
> > Hello, I've tested with your patch. But the same problem was reproduced.
> > Currently, I'm trying to git bisect. If i done git bisect, i will let you know.
> 
> Hi, I've done git bisect. and panic at jbd2_journal_put_journal_head() is caused by 
> ae4647fb7654676fc44a97e86eb35f9f06b99f66: "jbd2: reduce journal_head size."
> I write just code patch which revert ae4647fb7654676fc44a97e86eb35f9f06b99f66 because
> I don't know the root cause. 
  This is really strange. I've verified the code and all the places
modifying b_jlist or b_modified are holding bh_state lock so we should be
safe...

Hum, but I remember I was debugging similar problems with bit fields in
btrfs on ia64 as well (see http://lwn.net/Articles/478657/). So I think what
has happened is that your compiler compiled bitfield access as 64-bit and
updates to b_jcount and b_jlist / b_modified crashed into one another. I
didn't hit it because my compiler was not so "clever".

Grumble. In this case I think bitfields are not worth the trouble with gcc.
It's a pitty we have to spend additional 8 bytes for every journal_head but
we'll survive... I'll send Ted a partial revert and add a comment so that
we won't repeat this mistake in future.

								Honza
 
> Signed-off-by: Eunbong Song <eunb.song@samsung.com>
> ---
>  include/linux/journal-head.h |   11 +++++++++--
>  1 files changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/journal-head.h b/include/linux/journal-head.h
> index 13a3da2..c18b46f 100644
> --- a/include/linux/journal-head.h
> +++ b/include/linux/journal-head.h
> @@ -31,14 +31,21 @@ struct journal_head {
>  	/*
>  	 * Journalling list for this buffer [jbd_lock_bh_state()]
>  	 */
> -	unsigned b_jlist:4;
> +	unsigned b_jlist;
>  
>  	/*
>  	 * This flag signals the buffer has been modified by
>  	 * the currently running transaction
>  	 * [jbd_lock_bh_state()]
>  	 */
> -	unsigned b_modified:1;
> +	unsigned b_modified;
> +
> +	/*
> +	 * This feild tracks the last transaction id in which this buffer
> +	 * has been cowed
> +	 * [jbd_lock_bh_state()]
> +	 */
> +	tid_t b_cow_tid;
>  
>  	/*
>  	 * Copy of the buffer data frozen for writing to the log.
> -- 
> 1.7.0.4
> 
> 
> Thanks. 
-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR

Re: EXT4 regression caused 4eec7

[Theodore Ts'o]

On Mon, May 13, 2013 at 03:18:09PM +0200, Jan Kara wrote:
> Grumble. In this case I think bitfields are not worth the trouble with gcc.
> It's a pitty we have to spend additional 8 bytes for every journal_head but
> we'll survive... I'll send Ted a partial revert and add a comment so that
> we won't repeat this mistake in future.

Or just switch things to use explicit 32-bit boolean operations.
Sounds the safest way to go is to simply not trust bitfields to be
something gcc is competent to compile correctly, and just open code it
in standard C.  (Large portions of ext4 and e2fsprogs do this
manually, for historical reasons, and it sounds like we have a good
reason to do it going forward.)

Jan, Dmitry --- I still have in my tree a revert for commit 4eec708d2:
ext4: use io_end for multiple bios, since I belive Dmitry still
bisected a regression for xfstests 299.  Dmitry, can you confirm that
you are definitely seeing a regression here?  Jan, do you mind if we
try to figure out how to fix this during the next development cycle,
since it was part of your much longer, extensive patch series anyway?

I've determined that the reason why I didn't see a problem was because
xfstests 299 was failing earlier on the baseline, and crashing my
regression tests.  So I simply commented it out just so I could
complete the testing.  It seems that xfstests 299 is problematic for
me, and I need to focus on how to make it pass successfully.  (Dmitry,
when I revert the commit which you identified, xfstests 299 is *still*
failing for me....) 

						- Ted

Re: EXT4 regression caused 4eec7

[Jan Kara]

On Mon 13-05-13 09:30:36, Ted Tso wrote:
> On Mon, May 13, 2013 at 03:18:09PM +0200, Jan Kara wrote:
> > Grumble. In this case I think bitfields are not worth the trouble with gcc.
> > It's a pitty we have to spend additional 8 bytes for every journal_head but
> > we'll survive... I'll send Ted a partial revert and add a comment so that
> > we won't repeat this mistake in future.
> 
> Or just switch things to use explicit 32-bit boolean operations.
> Sounds the safest way to go is to simply not trust bitfields to be
> something gcc is competent to compile correctly, and just open code it
> in standard C.  (Large portions of ext4 and e2fsprogs do this
> manually, for historical reasons, and it sounds like we have a good
> reason to do it going forward.)
  Yeah, but in this case b_jlist testing / setting would require accessor
functions which is slightly ugly. For now I just submitted a revert of the
bitfield part and if someone feels like saving 8 bytes in struct
journal_head is worth the hassle, then we can later go that route.

> Jan, Dmitry --- I still have in my tree a revert for commit 4eec708d2:
> ext4: use io_end for multiple bios, since I belive Dmitry still
> bisected a regression for xfstests 299.  Dmitry, can you confirm that
> you are definitely seeing a regression here?  Jan, do you mind if we
> try to figure out how to fix this during the next development cycle,
> since it was part of your much longer, extensive patch series anyway?
  Yeah, for now just send a revert to Linus. I'll look into that failure
now but since I didn't hit the problem in my testing it may take a while.

								Honza
-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR

Re: EXT4 regression caused 4eec7

[Dmitry Monakhov]

On Mon, 13 May 2013 09:30:36 -0400, Theodore Ts'o <tytso@mit.edu> wrote:
> On Mon, May 13, 2013 at 03:18:09PM +0200, Jan Kara wrote:
> > Grumble. In this case I think bitfields are not worth the trouble with gcc.
> > It's a pitty we have to spend additional 8 bytes for every journal_head but
> > we'll survive... I'll send Ted a partial revert and add a comment so that
> > we won't repeat this mistake in future.
> 
> Or just switch things to use explicit 32-bit boolean operations.
> Sounds the safest way to go is to simply not trust bitfields to be
> something gcc is competent to compile correctly, and just open code it
> in standard C.  (Large portions of ext4 and e2fsprogs do this
> manually, for historical reasons, and it sounds like we have a good
> reason to do it going forward.)
> 
> Jan, Dmitry --- I still have in my tree a revert for commit 4eec708d2:
> ext4: use io_end for multiple bios, since I belive Dmitry still
> bisected a regression for xfstests 299.  Dmitry, can you confirm that
> you are definitely seeing a regression here?
Yes, this patch provoke use-after-free which detected by slab sanity checks.
>  Jan, do you mind if we
> try to figure out how to fix this during the next development cycle,
> since it was part of your much longer, extensive patch series anyway?
> 
> I've determined that the reason why I didn't see a problem was because
> xfstests 299 was failing earlier on the baseline, and crashing my
> regression tests. So I simply commented it out just so I could
> complete the testing.  It seems that xfstests 299 is problematic for
> me, and I need to focus on how to make it pass successfully.  (Dmitry,
> when I revert the commit which you identified, xfstests 299 is *still*
> failing for me....) 
In fact generic/299 always succeed for me, but it produce warning
WARNING: at fs/ext4/inode.c:3218 ext4_ext_direct_IO
and complains from slab debug. But it was missed because i've missed
this error in the logs and forget to check /proc/sys/kernel/tained.
> 
> 						- Ted
> --
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Re: EXT4 regression caused 4eec7

[Theodore Ts'o]

On Mon, May 13, 2013 at 05:47:05PM +0400, Dmitry Monakhov wrote:
> In fact generic/299 always succeed for me, but it produce warning
> WARNING: at fs/ext4/inode.c:3218 ext4_ext_direct_IO
> and complains from slab debug. But it was missed because i've missed
> this error in the logs and forget to check /proc/sys/kernel/tained.

This is how it's failing for me....

generic/299		[23:06:27][  109.243220] fio (3376) used greatest stack depth: 5240 bytes left
[  109.252757] fio (3380) used greatest stack depth: 5140 bytes left
[  109.307227] fio (3374) used greatest stack depth: 4944 bytes left
 [23:08:10] [failed, exit status 1] - output mismatch (see /root/xfstests/results/generic/299.out.bad)
    --- tests/generic/299.out	2013-04-05 21:41:17.000000000 -0400
    +++ /root/xfstests/results/generic/299.out.bad	2013-05-11 23:08:10.835356876 -0400
    @@ -3,3 +3,6 @@
     Run fio with random aio-dio pattern
     
     Start fallocate/truncate loop
    +./common/rc: line 2055:  3335 Segmentation fault      "$@" >> $seqres.full 2>&1
    +failed: '/root/xfstests/bin/fio /tmp/3135-299.fio'
    +(see /root/xfstests/results/generic/299.full for details)
     ...
     (Run 'diff -u tests/generic/299.out /root/xfstests/results/generic/299.out.bad' to see the entire diff)

I haven't had a chance to investigate the core dump yet....

  	      	       	  	      	  - Ted

Re: Re: Re: EXT4 regression caused 4eec7

[Zheng Liu]

On Mon, May 13, 2013 at 03:18:09PM +0200, Jan Kara wrote:
> On Sun 12-05-13 13:04:59, EUNBONG SONG wrote:
> > 
> > 
> > >> Since at this point it's safer to rollback the change and we can
> > >> investigate more deeply how to fix it correctly for the next
> > >> development cycle, this is the patch which I'm testing.
> > 
> > >>                     - Ted
> > 
> > > Hello, I've tested with your patch. But the same problem was reproduced.
> > > Currently, I'm trying to git bisect. If i done git bisect, i will let you know.
> > 
> > Hi, I've done git bisect. and panic at jbd2_journal_put_journal_head() is caused by 
> > ae4647fb7654676fc44a97e86eb35f9f06b99f66: "jbd2: reduce journal_head size."
> > I write just code patch which revert ae4647fb7654676fc44a97e86eb35f9f06b99f66 because
> > I don't know the root cause. 
>   This is really strange. I've verified the code and all the places
> modifying b_jlist or b_modified are holding bh_state lock so we should be
> safe...

Hi Jan,

Could you please take a look at this mail [1].  I don't think we hold
bh_state lock there.

1. http://www.spinics.net/lists/linux-ext4/msg38205.html

Thanks,
                                                - Zheng

Re: EXT4 regression caused 4eec7

[Dmitry Monakhov]

On Mon, 13 May 2013 09:52:21 -0400, Theodore Ts'o <tytso@mit.edu> wrote:
> On Mon, May 13, 2013 at 05:47:05PM +0400, Dmitry Monakhov wrote:
> > In fact generic/299 always succeed for me, but it produce warning
> > WARNING: at fs/ext4/inode.c:3218 ext4_ext_direct_IO
> > and complains from slab debug. But it was missed because i've missed
> > this error in the logs and forget to check /proc/sys/kernel/tained.
> 
> This is how it's failing for me....
Because you ask questions, but do not read answers :)
http://marc.info/?l=linux-ext4&m=136580060822252&w=2
http://marc.info/?l=linux-ext4&m=136610044500931&w=2
> 
> generic/299		[23:06:27][  109.243220] fio (3376) used greatest stack depth: 5240 bytes left
> [  109.252757] fio (3380) used greatest stack depth: 5140 bytes left
> [  109.307227] fio (3374) used greatest stack depth: 4944 bytes left
>  [23:08:10] [failed, exit status 1] - output mismatch (see /root/xfstests/results/generic/299.out.bad)
>     --- tests/generic/299.out	2013-04-05 21:41:17.000000000 -0400
>     +++ /root/xfstests/results/generic/299.out.bad	2013-05-11 23:08:10.835356876 -0400
>     @@ -3,3 +3,6 @@
>      Run fio with random aio-dio pattern
>      
>      Start fallocate/truncate loop
>     +./common/rc: line 2055:  3335 Segmentation fault      "$@" >> $seqres.full 2>&1
>     +failed: '/root/xfstests/bin/fio /tmp/3135-299.fio'
>     +(see /root/xfstests/results/generic/299.full for details)
>      ...
>      (Run 'diff -u tests/generic/299.out /root/xfstests/results/generic/299.out.bad' to see the entire diff)
> 
> I haven't had a chance to investigate the core dump yet....
> 
>   	      	       	  	      	  - Ted
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> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: Re: Re: EXT4 regression caused 4eec7

[Jan Kara]

On Mon 13-05-13 21:56:43, Zheng Liu wrote:
> On Mon, May 13, 2013 at 03:18:09PM +0200, Jan Kara wrote:
> > On Sun 12-05-13 13:04:59, EUNBONG SONG wrote:
> > > 
> > > 
> > > >> Since at this point it's safer to rollback the change and we can
> > > >> investigate more deeply how to fix it correctly for the next
> > > >> development cycle, this is the patch which I'm testing.
> > > 
> > > >>                     - Ted
> > > 
> > > > Hello, I've tested with your patch. But the same problem was reproduced.
> > > > Currently, I'm trying to git bisect. If i done git bisect, i will let you know.
> > > 
> > > Hi, I've done git bisect. and panic at jbd2_journal_put_journal_head() is caused by 
> > > ae4647fb7654676fc44a97e86eb35f9f06b99f66: "jbd2: reduce journal_head size."
> > > I write just code patch which revert ae4647fb7654676fc44a97e86eb35f9f06b99f66 because
> > > I don't know the root cause. 
> >   This is really strange. I've verified the code and all the places
> > modifying b_jlist or b_modified are holding bh_state lock so we should be
> > safe...
> 
> Hi Jan,
> 
> Could you please take a look at this mail [1].  I don't think we hold
> bh_state lock there.
> 
> 1. http://www.spinics.net/lists/linux-ext4/msg38205.html
  I'll also reply to that thread but: Yes, we don't hold bh_state lock when
reading b_jlist in that one case (that's why I wrote 'modify' and not just
'access' in my previous email). But that's really harmless since we don't
do any complex operations with b_jlist (only get & set) so we either see an
old value or a new one. And that particular use is going away anyway later
in my series.

								Honza
-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR

Re: EXT4 regression caused 4eec7

[Eric Sandeen]

On 5/12/13 4:01 AM, Dmitry Monakhov wrote:
> In fact '4eec70' are vexing because I have reviewed and tested this patch before
> it was marked as Review-by, but missed the bug. This is because xfstests
> was executed manually logs was full of warnings but tainted flag was not
> checked at the end. 

Can you elaborate on this?  What was logged, and is it something we could
try to pick up post-test in xfstests?

Thanks,
-Eric

Re: Re: Re: EXT4 regression caused 4eec7

[Zheng Liu]

On Mon, May 13, 2013 at 05:17:27PM +0200, Jan Kara wrote:
> On Mon 13-05-13 21:56:43, Zheng Liu wrote:
> > On Mon, May 13, 2013 at 03:18:09PM +0200, Jan Kara wrote:
> > > On Sun 12-05-13 13:04:59, EUNBONG SONG wrote:
> > > > 
> > > > 
> > > > >> Since at this point it's safer to rollback the change and we can
> > > > >> investigate more deeply how to fix it correctly for the next
> > > > >> development cycle, this is the patch which I'm testing.
> > > > 
> > > > >>                     - Ted
> > > > 
> > > > > Hello, I've tested with your patch. But the same problem was reproduced.
> > > > > Currently, I'm trying to git bisect. If i done git bisect, i will let you know.
> > > > 
> > > > Hi, I've done git bisect. and panic at jbd2_journal_put_journal_head() is caused by 
> > > > ae4647fb7654676fc44a97e86eb35f9f06b99f66: "jbd2: reduce journal_head size."
> > > > I write just code patch which revert ae4647fb7654676fc44a97e86eb35f9f06b99f66 because
> > > > I don't know the root cause. 
> > >   This is really strange. I've verified the code and all the places
> > > modifying b_jlist or b_modified are holding bh_state lock so we should be
> > > safe...
> > 
> > Hi Jan,
> > 
> > Could you please take a look at this mail [1].  I don't think we hold
> > bh_state lock there.
> > 
> > 1. http://www.spinics.net/lists/linux-ext4/msg38205.html
>   I'll also reply to that thread but: Yes, we don't hold bh_state lock when
> reading b_jlist in that one case (that's why I wrote 'modify' and not just
> 'access' in my previous email). But that's really harmless since we don't
> do any complex operations with b_jlist (only get & set) so we either see an
> old value or a new one. And that particular use is going away anyway later
> in my series.

I see.  Thanks for your explanation.

                                                - Zheng

Re: EXT4 regression caused 4eec7

[Jan Kara]

On Mon 13-05-13 11:34:12, Eric Sandeen wrote:
> On 5/12/13 4:01 AM, Dmitry Monakhov wrote:
> > In fact '4eec70' are vexing because I have reviewed and tested this patch before
> > it was marked as Review-by, but missed the bug. This is because xfstests
> > was executed manually logs was full of warnings but tainted flag was not
> > checked at the end. 
> 
> Can you elaborate on this?  What was logged, and is it something we could
> try to pick up post-test in xfstests?
  Generally I think it might be useful if xfstests would fail / warn if
kernel became tainted during the test (e.g. due to WARN_ON or oops, or
something like that). It should be even relatively easy to implement
(just compare /proc/sys/kernel/tainted before and after each test).

								Honza
-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR

Re: EXT4 regression caused 4eec7

[Eric Sandeen]

On 5/13/13 12:01 PM, Jan Kara wrote:
> On Mon 13-05-13 11:34:12, Eric Sandeen wrote:
>> On 5/12/13 4:01 AM, Dmitry Monakhov wrote:
>>> In fact '4eec70' are vexing because I have reviewed and tested this patch before
>>> it was marked as Review-by, but missed the bug. This is because xfstests
>>> was executed manually logs was full of warnings but tainted flag was not
>>> checked at the end. 
>>
>> Can you elaborate on this?  What was logged, and is it something we could
>> try to pick up post-test in xfstests?
>   Generally I think it might be useful if xfstests would fail / warn if
> kernel became tainted during the test (e.g. due to WARN_ON or oops, or
> something like that). It should be even relatively easy to implement
> (just compare /proc/sys/kernel/tainted before and after each test).
> 
> 								Honza
> 

Ah, right.  That should be easy, I'll see if I can cook that up.

Thanks,
-Eric

Re: EXT4 regression caused 4eec7

[Theodore Ts'o]

On Mon, May 13, 2013 at 05:59:25PM +0400, Dmitry Monakhov wrote:
> > This is how it's failing for me....
> Because you ask questions, but do not read answers :)
> http://marc.info/?l=linux-ext4&m=136580060822252&w=2
> http://marc.info/?l=linux-ext4&m=136610044500931&w=2

Sorry, I thought I was running with the updated fio, but apparently I
was using an old xfstests.tar.gz tarball on my KVM image.  Mea culpa....

    	     	 		 	 - Ted

Re: EXT4 regression caused 4eec7

[Dmitry Monakhov]

On Mon, 13 May 2013 12:09:22 -0500, Eric Sandeen <sandeen@redhat.com> wrote:
> On 5/13/13 12:01 PM, Jan Kara wrote:
> > On Mon 13-05-13 11:34:12, Eric Sandeen wrote:
> >> On 5/12/13 4:01 AM, Dmitry Monakhov wrote:
> >>> In fact '4eec70' are vexing because I have reviewed and tested this patch before
> >>> it was marked as Review-by, but missed the bug. This is because xfstests
> >>> was executed manually logs was full of warnings but tainted flag was not
> >>> checked at the end. 
> >>
> >> Can you elaborate on this?  What was logged, and is it something we could
> >> try to pick up post-test in xfstests?
> >   Generally I think it might be useful if xfstests would fail / warn if
> > kernel became tainted during the test (e.g. due to WARN_ON or oops, or
> > something like that). It should be even relatively easy to implement
> > (just compare /proc/sys/kernel/tainted before and after each test).
> > 
> > 								Honza
> > 
> 
> Ah, right.  That should be easy, I'll see if I can cook that up.
Also we can use abrt's kernel-oops handler to collect messages.
> 
> Thanks,
> -Eric
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Re: EXT4 regression caused 4eec7

[Eric Sandeen]

On 5/14/13 2:11 AM, Dmitry Monakhov wrote:
> On Mon, 13 May 2013 12:09:22 -0500, Eric Sandeen <sandeen@redhat.com> wrote:
>> On 5/13/13 12:01 PM, Jan Kara wrote:
>>> On Mon 13-05-13 11:34:12, Eric Sandeen wrote:
>>>> On 5/12/13 4:01 AM, Dmitry Monakhov wrote:
>>>>> In fact '4eec70' are vexing because I have reviewed and tested this patch before
>>>>> it was marked as Review-by, but missed the bug. This is because xfstests
>>>>> was executed manually logs was full of warnings but tainted flag was not
>>>>> checked at the end. 
>>>>
>>>> Can you elaborate on this?  What was logged, and is it something we could
>>>> try to pick up post-test in xfstests?
>>>   Generally I think it might be useful if xfstests would fail / warn if
>>> kernel became tainted during the test (e.g. due to WARN_ON or oops, or
>>> something like that). It should be even relatively easy to implement
>>> (just compare /proc/sys/kernel/tainted before and after each test).
>>>
>>> 								Honza
>>>
>>
>> Ah, right.  That should be easy, I'll see if I can cook that up.
> Also we can use abrt's kernel-oops handler to collect messages.

I sent a pretty simple patch to just check the sysctl to the xfs list
yesterday.

-Eric

Re: EXT4 regression caused 4eec7

[Jan Kara]

On Sun 12-05-13 13:01:11, Dmitry Monakhov wrote:
> On Sat, 11 May 2013 19:05:59 -0400, Theodore Ts'o <tytso@mit.edu> wrote:
> > On Sat, May 11, 2013 at 03:00:53PM +0400, Dmitry Monakhov wrote:
> > > I've bisected ext4 related issue. It is appeared that it is pure ext4
> > > specific. Regression caused by  following commit
> > > commit 4eec708d263f0ee10861d69251708a225b64cac7
> > > Author: Jan Kara <jack@suse.cz>
> > > Date:   Thu Apr 11 23:56:53 2013 -0400
> > >     ext4: use io_end for multiple bios
> > 
> > Hmm... the next question is why did I see this in my testing.  Did you
> > find this on ia64, or x86?
> No simple x86_64. 
> > Also what about the slab corruption which
> > you saw when running XFS; was that unrelated?
> My theory about mysterious corruption in mm layer which broke everything
> was wrong. We have to absolutely independent regressions in  different
> filesystems:
> * Slub corruption on XFS
>   - testcase: xfstests/generic/007
>   - bad commit: 666d64 
>   - LINK: https://lkml.org/lkml/2013/5/11/154
> 
> * Slub corruption on EXT4
>   - testcase: xfstests/generic/299
>   - bad commit: 4eec70
>   - link: https://lkml.org/lkml/2013/5/11/37
>   - fix: https://lkml.org/lkml/2013/5/11/142
> 
> In fact '4eec70' are vexing because I have reviewed and tested this patch
> before it was marked as Review-by, but missed the bug. This is because
> xfstests was executed manually logs was full of warnings but tainted flag
> was not checked at the end. To prevent this thing in future I'll always
> use my local autotest(http://autotest.github.io/) farm next time.
  OK, so I finally nailed this down. DIO code has that peculiarity that it
doesn't call ->end_io callback when no IO was actually submitted. As a
bonus the generic code does a cleanup of generic stuff that is otherwise left
to ->end_io callback. Since I need to do io_end cleanup in ->end_io callback
I have to compensate for that in ext4_ext_direct_IO(). Sadly I've got the
condition wrong and also forgot that generic code already decremented
i_dio_count in the error failure case so cleanup sometimes happened twice.
I'll add fixed version of the patch back in my series (since the patch got
reverted upstream).

								Honza
-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR