Snapshots was allowed to mount as read-write and attempt to write to that snapshot lead a kernel panic #6510
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We should add a check in zpl_remount_fs |
behlendorf
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Aug 17, 2017
It's not enough to preserve/restore MS_RDONLY on the superblock flags to avoid remounting a snapshot read-write: be explicit about our intentions to the VFS layer so the readonly bit is updated correctly in do_remount_sb(). Reviewed-by: Chunwei Chen <tuxoko@gmail.com> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: loli10K <ezomori.nozomu@gmail.com> Closes #6510 Closes #6515
tonyhutter
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Aug 22, 2017
It's not enough to preserve/restore MS_RDONLY on the superblock flags to avoid remounting a snapshot read-write: be explicit about our intentions to the VFS layer so the readonly bit is updated correctly in do_remount_sb(). Reviewed-by: Chunwei Chen <tuxoko@gmail.com> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: loli10K <ezomori.nozomu@gmail.com> Closes #6510 Closes #6515
Fabian-Gruenbichler
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Sep 29, 2017
It's not enough to preserve/restore MS_RDONLY on the superblock flags to avoid remounting a snapshot read-write: be explicit about our intentions to the VFS layer so the readonly bit is updated correctly in do_remount_sb(). Reviewed-by: Chunwei Chen <tuxoko@gmail.com> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: loli10K <ezomori.nozomu@gmail.com> Closes openzfs#6510 Closes openzfs#6515
FransUrbo
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Apr 28, 2019
It's not enough to preserve/restore MS_RDONLY on the superblock flags to avoid remounting a snapshot read-write: be explicit about our intentions to the VFS layer so the readonly bit is updated correctly in do_remount_sb(). Reviewed-by: Chunwei Chen <tuxoko@gmail.com> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: loli10K <ezomori.nozomu@gmail.com> Closes openzfs#6510 Closes openzfs#6515
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System information
The console screenshot are [removed link]
Describe the problem you're observing
I was suppressed at first when I discovered I could just
mount -o remount,rwa snapshot file system under the.zfs/snapshot/directory. When I trying to create a file in a rw mounted snapshot, expecting some errors, but the kernel then panics, the panic message is "dirtying snapshot!".Describe how to reproduce the problem
Create a snapshot;
Browse the snapshot from
.zfs/snapshot/or mount the snapshot directly;Run a
mount -o remount,rw <path>to remount the snapshot file system read-write;Modify the read-write mounted file system, such as creating new file or truncating exist file.
Include any warning/errors/backtraces from the system logs
[removed link]
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