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dbuf: Set dr_data when unoverriding after clone #15656

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merged 1 commit into from
Dec 12, 2023
Merged

dbuf: Set dr_data when unoverriding after clone #15656

merged 1 commit into from
Dec 12, 2023

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amotin
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@amotin amotin commented Dec 9, 2023

Block cloning normally creates dirty record without dr_data. But if the block is read after cloning, it is moved into DB_CACHED state and receives the data buffer. If after that we call dbuf_unoverride() to convert the dirty record into normal write, we should give it the data buffer from dbuf and release one.

Fixes: #15654

Types of changes

  • Bug fix (non-breaking change which fixes an issue)
  • New feature (non-breaking change which adds functionality)
  • Performance enhancement (non-breaking change which improves efficiency)
  • Code cleanup (non-breaking change which makes code smaller or more readable)
  • Breaking change (fix or feature that would cause existing functionality to change)
  • Library ABI change (libzfs, libzfs_core, libnvpair, libuutil and libzfsbootenv)
  • Documentation (a change to man pages or other documentation)

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@amotin amotin added the Status: Code Review Needed Ready for review and testing label Dec 9, 2023
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amotin commented Dec 9, 2023

@pjd @oromenahar @robn Please take a look.

@amotin amotin mentioned this pull request Dec 9, 2023
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@amotin
dbuf: Set dr_data when unoverriding after clone
a80aecf 
Block cloning normally creates dirty record without dr_data.  But if
the block is read after cloning, it is moved into DB_CACHED state and
receives the data buffer.  If after that we call dbuf_unoverride()
to convert the dirty record into normal write, we should give it the
data buffer from dbuf and release one.

Signed-off-by:	Alexander Motin <[email protected]>
Sponsored by:	iXsystems, Inc.
@amotin amotin force-pushed the dbuf_unoverride_release branch from 8c3151d to a80aecf Compare December 9, 2023 02:52
oromenahar
oromenahar approved these changes Dec 9, 2023
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based on your explanation and the code I think it makes sense. Thanks :)

e: I'm not really a user of the mmap()-syscall. But from what robn wrote and what I expect from mmap() it should be acting like you described @amotin

@oromenahar oromenahar mentioned this pull request Dec 9, 2023
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@kevans91
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To be clear; is this just an accounting error, or would we have effectively dropped the dirtied contents on the floor (and retained the cloned block?) by not transitioning it into dr_data?

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amotin commented Dec 11, 2023

@kevans91 I haven't tried to reproduce it beyond the triggered assertion to observe other possible effects, but I'd think that missing arc_release() call may result in in-memory modification of snapshots, while empty dr_data in dirty record I'd expect to cause NULL-dereference during the transaction sync attempt, at least I don't see the NULL checks.

@KungFuJesus KungFuJesus mentioned this pull request Dec 11, 2023
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@behlendorf behlendorf added Status: Accepted Ready to integrate (reviewed, tested) and removed Status: Code Review Needed Ready for review and testing labels Dec 11, 2023
@amotin amotin mentioned this pull request Dec 12, 2023
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@behlendorf behlendorf merged commit 86e115e into openzfs:master Dec 12, 2023
25 of 26 checks passed
@amotin amotin deleted the dbuf_unoverride_release branch December 12, 2023 21:30
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robn commented Dec 12, 2023

@amotin well done!

ixhamza pushed a commit to ixhamza/zfs that referenced this pull request Dec 13, 2023
@amotin @ixhamza
dbuf: Set dr_data when unoverriding after clone
482b381 
Block cloning normally creates dirty record without dr_data.  But if
the block is read after cloning, it is moved into DB_CACHED state and
receives the data buffer.  If after that we call dbuf_unoverride()
to convert the dirty record into normal write, we should give it the
data buffer from dbuf and release one.

Reviewed-by: Kay Pedersen <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Alexander Motin <[email protected]>
Sponsored by: iXsystems, Inc.
Closes openzfs#15654
Closes openzfs#15656
ixhamza pushed a commit to truenas/zfs that referenced this pull request Dec 13, 2023
@amotin @ixhamza
dbuf: Set dr_data when unoverriding after clone
758c8da 
Block cloning normally creates dirty record without dr_data.  But if
the block is read after cloning, it is moved into DB_CACHED state and
receives the data buffer.  If after that we call dbuf_unoverride()
to convert the dirty record into normal write, we should give it the
data buffer from dbuf and release one.

Reviewed-by: Kay Pedersen <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Alexander Motin <[email protected]>
Sponsored by: iXsystems, Inc.
Closes openzfs#15654
Closes openzfs#15656
ixhamza pushed a commit to truenas/zfs that referenced this pull request Dec 13, 2023
@amotin @ixhamza
dbuf: Set dr_data when unoverriding after clone
ba69ae2 
Block cloning normally creates dirty record without dr_data.  But if
the block is read after cloning, it is moved into DB_CACHED state and
receives the data buffer.  If after that we call dbuf_unoverride()
to convert the dirty record into normal write, we should give it the
data buffer from dbuf and release one.

Reviewed-by: Kay Pedersen <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Alexander Motin <[email protected]>
Sponsored by: iXsystems, Inc.
Closes openzfs#15654
Closes openzfs#15656
ixhamza pushed a commit to truenas/zfs that referenced this pull request Dec 13, 2023
@amotin @ixhamza
dbuf: Set dr_data when unoverriding after clone
25ef79a 
Block cloning normally creates dirty record without dr_data.  But if
the block is read after cloning, it is moved into DB_CACHED state and
receives the data buffer.  If after that we call dbuf_unoverride()
to convert the dirty record into normal write, we should give it the
data buffer from dbuf and release one.

Reviewed-by: Kay Pedersen <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Alexander Motin <[email protected]>
Sponsored by: iXsystems, Inc.
Closes openzfs#15654
Closes openzfs#15656
mmatuska pushed a commit to mmatuska/zfs that referenced this pull request Dec 26, 2023
@amotin @mmatuska
dbuf: Set dr_data when unoverriding after clone
edc3764 
Block cloning normally creates dirty record without dr_data.  But if
the block is read after cloning, it is moved into DB_CACHED state and
receives the data buffer.  If after that we call dbuf_unoverride()
to convert the dirty record into normal write, we should give it the
data buffer from dbuf and release one.

Reviewed-by: Kay Pedersen <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Alexander Motin <[email protected]>
Sponsored by: iXsystems, Inc.
Closes openzfs#15654
Closes openzfs#15656
@mmatuska mmatuska mentioned this pull request Dec 26, 2023
Merged
13 tasks
mmatuska pushed a commit to mmatuska/zfs that referenced this pull request Dec 27, 2023
@amotin @mmatuska
dbuf: Set dr_data when unoverriding after clone
ea6e518 
Block cloning normally creates dirty record without dr_data.  But if
the block is read after cloning, it is moved into DB_CACHED state and
receives the data buffer.  If after that we call dbuf_unoverride()
to convert the dirty record into normal write, we should give it the
data buffer from dbuf and release one.

Reviewed-by: Kay Pedersen <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Alexander Motin <[email protected]>
Sponsored by: iXsystems, Inc.
Closes openzfs#15654
Closes openzfs#15656
mmatuska pushed a commit to mmatuska/zfs that referenced this pull request Dec 27, 2023
@amotin @mmatuska
dbuf: Set dr_data when unoverriding after clone
ef34c71 
Block cloning normally creates dirty record without dr_data.  But if
the block is read after cloning, it is moved into DB_CACHED state and
receives the data buffer.  If after that we call dbuf_unoverride()
to convert the dirty record into normal write, we should give it the
data buffer from dbuf and release one.

Reviewed-by: Kay Pedersen <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Alexander Motin <[email protected]>
Sponsored by: iXsystems, Inc.
Closes openzfs#15654
Closes openzfs#15656
@usaleem-ix usaleem-ix mentioned this pull request Dec 28, 2023
Merged
13 tasks
behlendorf pushed a commit that referenced this pull request Jan 9, 2024
@amotin @behlendorf
dbuf: Set dr_data when unoverriding after clone
9c40ae0 
Block cloning normally creates dirty record without dr_data.  But if
the block is read after cloning, it is moved into DB_CACHED state and
receives the data buffer.  If after that we call dbuf_unoverride()
to convert the dirty record into normal write, we should give it the
data buffer from dbuf and release one.

Reviewed-by: Kay Pedersen <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Alexander Motin <[email protected]>
Sponsored by: iXsystems, Inc.
Closes #15654
Closes #15656
@rincebrain rincebrain mentioned this pull request Mar 10, 2024
Closed
lundman pushed a commit to openzfsonwindows/openzfs that referenced this pull request Mar 13, 2024
@amotin @lundman
dbuf: Set dr_data when unoverriding after clone
791f6a1 
Block cloning normally creates dirty record without dr_data.  But if
the block is read after cloning, it is moved into DB_CACHED state and
receives the data buffer.  If after that we call dbuf_unoverride()
to convert the dirty record into normal write, we should give it the
data buffer from dbuf and release one.

Reviewed-by: Kay Pedersen <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Alexander Motin <[email protected]>
Sponsored by: iXsystems, Inc.
Closes openzfs#15654
Closes openzfs#15656
lundman pushed a commit to openzfsonwindows/openzfs that referenced this pull request Mar 13, 2024
@amotin @lundman
dbuf: Set dr_data when unoverriding after clone
32a8c18 
Block cloning normally creates dirty record without dr_data.  But if
the block is read after cloning, it is moved into DB_CACHED state and
receives the data buffer.  If after that we call dbuf_unoverride()
to convert the dirty record into normal write, we should give it the
data buffer from dbuf and release one.

Reviewed-by: Kay Pedersen <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Alexander Motin <[email protected]>
Sponsored by: iXsystems, Inc.
Closes openzfs#15654
Closes openzfs#15656
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@oromenahar oromenahar oromenahar approved these changes

@behlendorf behlendorf behlendorf approved these changes

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clone+mmap+write trips assert: VERIFY(arc_released(db->db_buf)) failed at dbuf.c:2150:dbuf_redirty()
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