Remove incorrect assertion #11235
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Remove incorrect assertion #11235
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Commit 85703f6 added a new ASSERT to zfs_write() as part of the cleanup which isn't correct in the case where multiple processes are concurrently extending a file. The `zp->z_size` is updated atomically while holding a range lock on only a portion of the file. Therefore, it's possible for the file size to increase after a same check is performed earlier in the loop causing this ASSERT to fail. The code itself handles this case correctly so only the invalid ASSERT needs to be removed. Signed-off-by: Brian Behlendorf <[email protected]>
bwatkinson
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Nov 23, 2020
ghost
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Nov 24, 2020
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Status: Accepted
behlendorf
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Dec 23, 2020
Commit 85703f6 added a new ASSERT to zfs_write() as part of the cleanup which isn't correct in the case where multiple processes are concurrently extending a file. The `zp->z_size` is updated atomically while holding a range lock on only a portion of the file. Therefore, it's possible for the file size to increase after a same check is performed earlier in the loop causing this ASSERT to fail. The code itself handles this case correctly so only the invalid ASSERT needs to be removed. Reviewed-by: Brian Atkinson <[email protected]> Reviewed-by: Ryan Moeller <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #11235
jsai20
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Commit 85703f6 added a new ASSERT to zfs_write() as part of the cleanup which isn't correct in the case where multiple processes are concurrently extending a file. The `zp->z_size` is updated atomically while holding a range lock on only a portion of the file. Therefore, it's possible for the file size to increase after a same check is performed earlier in the loop causing this ASSERT to fail. The code itself handles this case correctly so only the invalid ASSERT needs to be removed. Reviewed-by: Brian Atkinson <[email protected]> Reviewed-by: Ryan Moeller <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes openzfs#11235
sempervictus
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May 31, 2021
Commit 85703f6 added a new ASSERT to zfs_write() as part of the cleanup which isn't correct in the case where multiple processes are concurrently extending a file. The `zp->z_size` is updated atomically while holding a range lock on only a portion of the file. Therefore, it's possible for the file size to increase after a same check is performed earlier in the loop causing this ASSERT to fail. The code itself handles this case correctly so only the invalid ASSERT needs to be removed. Reviewed-by: Brian Atkinson <[email protected]> Reviewed-by: Ryan Moeller <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes openzfs#11235
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Motivation and Context
Resolve an incorrect assertion failure observed during testing.
Description
Commit 85703f6 added a new ASSERT to zfs_write() as part of the
cleanup which isn't correct in the case where multiple processes
are concurrently extending a file. The
zp->z_sizeis updatedatomically while holding a range lock on only a portion of the
file. Therefore, it's possible for the file size to increase
after a same check is performed earlier in the loop causing this
ASSERT to fail. The code itself handles this case correctly so
only the invalid ASSERT needs to be removed.
How Has This Been Tested?
The code was manually instrumented to verify the root cause.
The
xddutility was able to immediately reproduce the issuewith the following command line.
Types of changes
Checklist:
Signed-off-by.