diff mbox

[3/7] ext2: Avoid DAX zeroing to corrupt data

Message ID 1462960733-29634-4-git-send-email-jack@suse.cz (mailing list archive)
State Not Applicable
Headers show

Commit Message

Jan Kara May 11, 2016, 9:58 a.m. UTC
Currently ext2 zeroes any data blocks allocated for DAX inode however it
still returns them as BH_New. Thus DAX code zeroes them again in
dax_insert_mapping() which can possibly overwrite the data that has been
already stored to those blocks by a racing dax_io(). Avoid marking
pre-zeroed buffers as new.

Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/ext2/inode.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Ross Zwisler May 12, 2016, 6:45 p.m. UTC | #1
On Wed, May 11, 2016 at 11:58:49AM +0200, Jan Kara wrote:
> Currently ext2 zeroes any data blocks allocated for DAX inode however it
> still returns them as BH_New. Thus DAX code zeroes them again in
> dax_insert_mapping() which can possibly overwrite the data that has been
> already stored to those blocks by a racing dax_io(). Avoid marking
> pre-zeroed buffers as new.
> 
> Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
> Signed-off-by: Jan Kara <jack@suse.cz>
> ---
>  fs/ext2/inode.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
> index 6bd58e6ff038..1f07b758b968 100644
> --- a/fs/ext2/inode.c
> +++ b/fs/ext2/inode.c
> @@ -745,11 +745,11 @@ static int ext2_get_blocks(struct inode *inode,
>  			mutex_unlock(&ei->truncate_mutex);
>  			goto cleanup;
>  		}
> -	}
> +	} else
> +		set_buffer_new(bh_result);
>  
>  	ext2_splice_branch(inode, iblock, partial, indirect_blks, count);
>  	mutex_unlock(&ei->truncate_mutex);
> -	set_buffer_new(bh_result);
>  got_it:
>  	map_bh(bh_result, inode->i_sb, le32_to_cpu(chain[depth-1].key));
>  	if (count > blocks_to_boundary)
> -- 
> 2.6.6

Interestingly this change is causing a bunch of xfstests regressions for me
with ext2 + DAX.  All of these tests pass without this one change.

# ./check generic/075 generic/091 generic/112 generic/127 generic/231 generic/263
FSTYP         -- ext2
PLATFORM      -- Linux/x86_64 alara 4.6.0-rc5+
MKFS_OPTIONS  -- /dev/pmem0p2
MOUNT_OPTIONS -- -o dax -o context=system_u:object_r:nfs_t:s0 /dev/pmem0p2 /mnt/xfstests_scratch

generic/075 2s ... [failed, exit status 1] - output mismatch (see /root/xfstests/results//generic/075.out.bad)
    --- tests/generic/075.out	2015-10-02 10:19:36.798795839 -0600
    +++ /root/xfstests/results//generic/075.out.bad	2016-05-12 12:40:06.558706982 -0600
    @@ -4,15 +4,5 @@
     -----------------------------------------------
     fsx.0 : -d -N numops -S 0
     -----------------------------------------------
    -
    ------------------------------------------------
    -fsx.1 : -d -N numops -S 0 -x
    ------------------------------------------------
    ...
    (Run 'diff -u tests/generic/075.out /root/xfstests/results//generic/075.out.bad'  to see the entire diff)
generic/091 1s ... [failed, exit status 1] - output mismatch (see /root/xfstests/results//generic/091.out.bad)
    --- tests/generic/091.out	2015-10-02 10:19:36.800795853 -0600
    +++ /root/xfstests/results//generic/091.out.bad	2016-05-12 12:40:07.366712217 -0600
    @@ -1,7 +1,110 @@
     QA output created by 091
     fsx -N 10000 -l 500000 -r PSIZE -t BSIZE -w BSIZE -Z -R -W
    -fsx -N 10000 -o 8192 -l 500000 -r PSIZE -t BSIZE -w BSIZE -Z -R -W
    -fsx -N 10000 -o 32768 -l 500000 -r PSIZE -t BSIZE -w BSIZE -Z -R -W
    -fsx -N 10000 -o 8192 -l 500000 -r PSIZE -t BSIZE -w BSIZE -Z -R -W
    -fsx -N 10000 -o 32768 -l 500000 -r PSIZE -t BSIZE -w BSIZE -Z -R -W
    -fsx -N 10000 -o 128000 -l 500000 -r PSIZE -t BSIZE -w BSIZE -Z -W
    ...
    (Run 'diff -u tests/generic/091.out /root/xfstests/results//generic/091.out.bad'  to see the entire diff)
generic/112 2s ... [failed, exit status 1] - output mismatch (see /root/xfstests/results//generic/112.out.bad)
    --- tests/generic/112.out	2015-10-02 10:19:36.802795866 -0600
    +++ /root/xfstests/results//generic/112.out.bad	2016-05-12 12:40:08.601720218 -0600
    @@ -4,15 +4,5 @@
     -----------------------------------------------
     fsx.0 : -A -d -N numops -S 0
     -----------------------------------------------
    -
    ------------------------------------------------
    -fsx.1 : -A -d -N numops -S 0 -x
    ------------------------------------------------
    ...
    (Run 'diff -u tests/generic/112.out /root/xfstests/results//generic/112.out.bad'  to see the entire diff)
generic/127 14s ... - output mismatch (see /root/xfstests/results//generic/127.out.bad)
    --- tests/generic/127.out	2016-02-17 16:02:40.110656181 -0700
    +++ /root/xfstests/results//generic/127.out.bad	2016-05-12 12:40:16.861773730 -0600
    @@ -4,10 +4,905 @@
     === FSX Light Mode, Memory Mapping ===
     All 100000 operations completed A-OK!
     === FSX Standard Mode, No Memory Mapping ===
    -All 100000 operations completed A-OK!
    +ltp/fsx -q -l 262144 -o 65536 -S 191110531 -N 100000 -R -W fsx_std_nommap
    +READ BAD DATA: offset = 0xd72d, size = 0x826b, fname = /mnt/xfstests_test/fsx_std_nommap
    +OFFSET	GOOD	BAD	RANGE
    ...
    (Run 'diff -u tests/generic/127.out /root/xfstests/results//generic/127.out.bad'  to see the entire diff)
generic/231 22s ... [failed, exit status 1] - output mismatch (see /root/xfstests/results//generic/231.out.bad)
    --- tests/generic/231.out	2016-02-17 16:02:40.120656239 -0700
    +++ /root/xfstests/results//generic/231.out.bad	2016-05-12 12:40:19.266789311 -0600
    @@ -1,16 +1,1802 @@
     QA output created by 231
     === FSX Standard Mode, Memory Mapping, 1 Tasks ===
    -All 20000 operations completed A-OK!
    -Comparing user usage
    -Comparing group usage
    -=== FSX Standard Mode, Memory Mapping, 4 Tasks ===
    -All 20000 operations completed A-OK!
    ...
    (Run 'diff -u tests/generic/231.out /root/xfstests/results//generic/231.out.bad'  to see the entire diff)
generic/263 1s ... [failed, exit status 1] - output mismatch (see /root/xfstests/results//generic/263.out.bad)
    --- tests/generic/263.out	2015-10-02 10:19:36.807795900 -0600
    +++ /root/xfstests/results//generic/263.out.bad	2016-05-12 12:40:19.801792777 -0600
    @@ -1,3 +1,1429 @@
     QA output created by 263
     fsx -N 10000 -o 8192 -l 500000 -r PSIZE -t BSIZE -w BSIZE -Z
    -fsx -N 10000 -o 128000 -l 500000 -r PSIZE -t BSIZE -w BSIZE -Z
    +main: filesystem does not support fallocate mode 0, disabling!
    +main: filesystem does not support fallocate mode FALLOC_FL_KEEP_SIZE, disabling!
    +main: filesystem does not support fallocate mode FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, disabling!
    +main: filesystem does not support fallocate mode FALLOC_FL_ZERO_RANGE, disabling!
    ...
    (Run 'diff -u tests/generic/263.out /root/xfstests/results//generic/263.out.bad'  to see the entire diff)
Ran: generic/075 generic/091 generic/112 generic/127 generic/231 generic/263
Failures: generic/075 generic/091 generic/112 generic/127 generic/231 generic/263
Failed 6 of 6 tests
Jan Kara May 16, 2016, 3:22 p.m. UTC | #2
On Thu 12-05-16 12:45:22, Ross Zwisler wrote:
> On Wed, May 11, 2016 at 11:58:49AM +0200, Jan Kara wrote:
> > Currently ext2 zeroes any data blocks allocated for DAX inode however it
> > still returns them as BH_New. Thus DAX code zeroes them again in
> > dax_insert_mapping() which can possibly overwrite the data that has been
> > already stored to those blocks by a racing dax_io(). Avoid marking
> > pre-zeroed buffers as new.
> > 
> > Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
> > Signed-off-by: Jan Kara <jack@suse.cz>
> > ---
> >  fs/ext2/inode.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
> > index 6bd58e6ff038..1f07b758b968 100644
> > --- a/fs/ext2/inode.c
> > +++ b/fs/ext2/inode.c
> > @@ -745,11 +745,11 @@ static int ext2_get_blocks(struct inode *inode,
> >  			mutex_unlock(&ei->truncate_mutex);
> >  			goto cleanup;
> >  		}
> > -	}
> > +	} else
> > +		set_buffer_new(bh_result);
> >  
> >  	ext2_splice_branch(inode, iblock, partial, indirect_blks, count);
> >  	mutex_unlock(&ei->truncate_mutex);
> > -	set_buffer_new(bh_result);
> >  got_it:
> >  	map_bh(bh_result, inode->i_sb, le32_to_cpu(chain[depth-1].key));
> >  	if (count > blocks_to_boundary)
> > -- 
> > 2.6.6
> 
> Interestingly this change is causing a bunch of xfstests regressions for me
> with ext2 + DAX.  All of these tests pass without this one change.

Good catch. Attached patch fixes this issue for me. Preferably it should be
merged before the above ext2 change.

								Honza
Verma, Vishal L May 17, 2016, 6:52 a.m. UTC | #3
On Mon, 2016-05-16 at 17:22 +0200, Jan Kara wrote:
> On Thu 12-05-16 12:45:22, Ross Zwisler wrote:

> > 

> > On Wed, May 11, 2016 at 11:58:49AM +0200, Jan Kara wrote:

> > > 

> > > Currently ext2 zeroes any data blocks allocated for DAX inode

> > > however it

> > > still returns them as BH_New. Thus DAX code zeroes them again in

> > > dax_insert_mapping() which can possibly overwrite the data that

> > > has been

> > > already stored to those blocks by a racing dax_io(). Avoid

> > > marking

> > > pre-zeroed buffers as new.

> > > 

> > > Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>

> > > Signed-off-by: Jan Kara <jack@suse.cz>

> > > ---

> > >  fs/ext2/inode.c | 4 ++--

> > >  1 file changed, 2 insertions(+), 2 deletions(-)

> > > 

> > > diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c

> > > index 6bd58e6ff038..1f07b758b968 100644

> > > --- a/fs/ext2/inode.c

> > > +++ b/fs/ext2/inode.c

> > > @@ -745,11 +745,11 @@ static int ext2_get_blocks(struct inode

> > > *inode,

> > >  			mutex_unlock(&ei->truncate_mutex);

> > >  			goto cleanup;

> > >  		}

> > > -	}

> > > +	} else

> > > +		set_buffer_new(bh_result);

> > >  

> > >  	ext2_splice_branch(inode, iblock, partial,

> > > indirect_blks, count);

> > >  	mutex_unlock(&ei->truncate_mutex);

> > > -	set_buffer_new(bh_result);

> > >  got_it:

> > >  	map_bh(bh_result, inode->i_sb, le32_to_cpu(chain[depth-

> > > 1].key));

> > >  	if (count > blocks_to_boundary)

> > > -- 

> > > 2.6.6

> > Interestingly this change is causing a bunch of xfstests

> > regressions for me

> > with ext2 + DAX.  All of these tests pass without this one change.

> Good catch. Attached patch fixes this issue for me. Preferably it

> should be

> merged before the above ext2 change.

> 

> 								Honza


Hey Jan,

In my patch 3 of the error handling series, I have:

-               err = dax_clear_sectors(inode->i_sb->s_bdev,
-                               le32_to_cpu(chain[depth-1].key) <<
-                               (inode->i_blkbits - 9),
-                               1 << inode->i_blkbits);
+               err = sb_issue_zeroout(inode->i_sb,
+                               le32_to_cpu(chain[depth-1].key), 1, GFP_NOFS);

Does this mean I have to change to send the sb_issue_zeroout for
'count' blocks.. i.e.

-               err = dax_clear_sectors(inode->i_sb->s_bdev,
-                               le32_to_cpu(chain[depth-1].key) <<
-                               (inode->i_blkbits - 9),
-                               1 << inode->i_blkbits);
+               err = sb_issue_zeroout(inode->i_sb,
+                               le32_to_cpu(chain[depth-1].key), count, GFP_NOFS);

If so, I'll update my series tomorrow to include in both of these changes.

Thanks,
	-Vishal
Jan Kara May 17, 2016, 7:19 a.m. UTC | #4
On Tue 17-05-16 06:52:47, Verma, Vishal L wrote:
> On Mon, 2016-05-16 at 17:22 +0200, Jan Kara wrote:
> > On Thu 12-05-16 12:45:22, Ross Zwisler wrote:
> > > 
> > > On Wed, May 11, 2016 at 11:58:49AM +0200, Jan Kara wrote:
> > > > 
> > > > Currently ext2 zeroes any data blocks allocated for DAX inode
> > > > however it
> > > > still returns them as BH_New. Thus DAX code zeroes them again in
> > > > dax_insert_mapping() which can possibly overwrite the data that
> > > > has been
> > > > already stored to those blocks by a racing dax_io(). Avoid
> > > > marking
> > > > pre-zeroed buffers as new.
> > > > 
> > > > Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
> > > > Signed-off-by: Jan Kara <jack@suse.cz>
> > > > ---
> > > >  fs/ext2/inode.c | 4 ++--
> > > >  1 file changed, 2 insertions(+), 2 deletions(-)
> > > > 
> > > > diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
> > > > index 6bd58e6ff038..1f07b758b968 100644
> > > > --- a/fs/ext2/inode.c
> > > > +++ b/fs/ext2/inode.c
> > > > @@ -745,11 +745,11 @@ static int ext2_get_blocks(struct inode
> > > > *inode,
> > > >  			mutex_unlock(&ei->truncate_mutex);
> > > >  			goto cleanup;
> > > >  		}
> > > > -	}
> > > > +	} else
> > > > +		set_buffer_new(bh_result);
> > > >  
> > > >  	ext2_splice_branch(inode, iblock, partial,
> > > > indirect_blks, count);
> > > >  	mutex_unlock(&ei->truncate_mutex);
> > > > -	set_buffer_new(bh_result);
> > > >  got_it:
> > > >  	map_bh(bh_result, inode->i_sb, le32_to_cpu(chain[depth-
> > > > 1].key));
> > > >  	if (count > blocks_to_boundary)
> > > > -- 
> > > > 2.6.6
> > > Interestingly this change is causing a bunch of xfstests
> > > regressions for me
> > > with ext2 + DAX.  All of these tests pass without this one change.
> > Good catch. Attached patch fixes this issue for me. Preferably it
> > should be
> > merged before the above ext2 change.
> > 
> > 								Honza
> 
> Hey Jan,
> 
> In my patch 3 of the error handling series, I have:
> 
> -               err = dax_clear_sectors(inode->i_sb->s_bdev,
> -                               le32_to_cpu(chain[depth-1].key) <<
> -                               (inode->i_blkbits - 9),
> -                               1 << inode->i_blkbits);
> +               err = sb_issue_zeroout(inode->i_sb,
> +                               le32_to_cpu(chain[depth-1].key), 1, GFP_NOFS);
> 
> Does this mean I have to change to send the sb_issue_zeroout for
> 'count' blocks.. i.e.

Yes, I've noticed the conflict today as well.

> -               err = dax_clear_sectors(inode->i_sb->s_bdev,
> -                               le32_to_cpu(chain[depth-1].key) <<
> -                               (inode->i_blkbits - 9),
> -                               1 << inode->i_blkbits);
> +               err = sb_issue_zeroout(inode->i_sb,
> +                               le32_to_cpu(chain[depth-1].key), count, GFP_NOFS);
> 
> If so, I'll update my series tomorrow to include in both of these changes.

I'd prefer these two to stay separate commits (they are really
independent).  Since you already depend on other patches from the DAX
cleanup series, just add this patch to the list of dependencies and base
your change on that... Hmm?

								Honza
Verma, Vishal L May 17, 2016, 5:56 p.m. UTC | #5
On Tue, 2016-05-17 at 09:19 +0200, Jan Kara wrote:
> On Tue 17-05-16 06:52:47, Verma, Vishal L wrote:


[...]

> > 

> > 

> > -               err = dax_clear_sectors(inode->i_sb->s_bdev,

> > -                               le32_to_cpu(chain[depth-1].key) <<

> > -                               (inode->i_blkbits - 9),

> > -                               1 << inode->i_blkbits);

> > +               err = sb_issue_zeroout(inode->i_sb,

> > +                               le32_to_cpu(chain[depth-1].key),

> > count, GFP_NOFS);

> > 

> > If so, I'll update my series tomorrow to include in both of these

> > changes.

> I'd prefer these two to stay separate commits (they are really

> independent).  Since you already depend on other patches from the DAX

> cleanup series, just add this patch to the list of dependencies and

> base

> your change on that... Hmm?


Yes I agree. I'm preparing a branch that adds your fix, and modifying my
sb_issue_zeroout to use the same fix. I've verified that those tests
pass after both changes.

Thanks!
	-Vishal
diff mbox

Patch

diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index 6bd58e6ff038..1f07b758b968 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -745,11 +745,11 @@  static int ext2_get_blocks(struct inode *inode,
 			mutex_unlock(&ei->truncate_mutex);
 			goto cleanup;
 		}
-	}
+	} else
+		set_buffer_new(bh_result);
 
 	ext2_splice_branch(inode, iblock, partial, indirect_blks, count);
 	mutex_unlock(&ei->truncate_mutex);
-	set_buffer_new(bh_result);
 got_it:
 	map_bh(bh_result, inode->i_sb, le32_to_cpu(chain[depth-1].key));
 	if (count > blocks_to_boundary)