Update the kstat dataset_name when renaming a zvol #15486
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Closes openzfs#15482 (for FreeBSD only) Sponsored-by: Axcient Signed-off-by: Alan Somers <asomers@gmail.com>
amotin
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Signed-off-by: Alan Somers <asomers@gmail.com> Sponsored-by: Axcient
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Yeah, it looks trivial, but I have no way to test it. |
We have reviews and CI, and it is trivial. I think divergence between platforms is worse than the risk. |
Closes openzfs#15482 (for Linux only) Sponsored-by: Axcient Signed-off-by: Alan Somers <asomers@gmail.com>
Very well, it's done. |
amotin
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behlendorf
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Add a dataset_kstats_rename function, and call it when renaming a zvol on FreeBSD and Linux. Reviewed-by: Alexander Motin <mav@FreeBSD.org> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Alan Somers <asomers@gmail.com> Sponsored-by: Axcient Closes openzfs#15482 Closes openzfs#15486
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Add a dataset_kstats_rename function, and call it when renaming a zvol on FreeBSD and Linux. Reviewed-by: Alexander Motin <mav@FreeBSD.org> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Alan Somers <asomers@gmail.com> Sponsored-by: Axcient Closes openzfs#15482 Closes openzfs#15486
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jgottula
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If a zvol is renamed, and it has one or more snapshots, and snapdev=visible is true for the zvol, then the rename causes a kernel null pointer dereference error. This has the effect (on Linux, anyway) of killing the z_zvol taskq kthread, with locks still held; which in turn causes a variety of zvol-related operations afterward to hang indefinitely (such as udev workers, among other things). The problem occurs because of an oversight in openzfs#15486 (e36ff84). As documented in dataset_kstats_create, some datasets may not actually have kstats allocated for them; and at least at the present time, this is true for snapshots. In practical terms, this means that for snapshots, dk->dk_kstats will be NULL. The dataset_kstats_rename function introduced in the patch above does not first check whether dk->dk_kstats is NULL before proceeding, unlike e.g. the nearby dataset_kstats_update_* functions. In the very particular circumstance in which a zvol is renamed, AND that zvol has one or more snapshots, AND that zvol also has snapdev=visible, zvol_rename_minors_impl will loop over not just the zvol dataset itself, but each of the zvol's snapshots as well, so that their device nodes will be renamed as well. This results in dataset_kstats_create being called for snapshots, where, as we've established, dk->dk_kstats is NULL. Fix this by simply adding a NULL check before doing anything in dataset_kstats_rename. This still allows the dataset_name kstat value for the zvol to be updated (as was the intent of the original patch), and merely blocks attempts by the code to act upon the zvol's non-kstat-having snapshots. If at some future time, kstats are added for snapshots, then things should work as intended in that case as well. Signed-off-by: Justin Gottula <justin@jgottula.com>
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If a zvol is renamed, and it has one or more snapshots, and snapdev=visible is true for the zvol, then the rename causes a kernel null pointer dereference error. This has the effect (on Linux, anyway) of killing the z_zvol taskq kthread, with locks still held; which in turn causes a variety of zvol-related operations afterward to hang indefinitely (such as udev workers, among other things). The problem occurs because of an oversight in openzfs#15486 (e36ff84). As documented in dataset_kstats_create, some datasets may not actually have kstats allocated for them; and at least at the present time, this is true for snapshots. In practical terms, this means that for snapshots, dk->dk_kstats will be NULL. The dataset_kstats_rename function introduced in the patch above does not first check whether dk->dk_kstats is NULL before proceeding, unlike e.g. the nearby dataset_kstats_update_* functions. In the very particular circumstance in which a zvol is renamed, AND that zvol has one or more snapshots, AND that zvol also has snapdev=visible, zvol_rename_minors_impl will loop over not just the zvol dataset itself, but each of the zvol's snapshots as well, so that their device nodes will be renamed as well. This results in dataset_kstats_create being called for snapshots, where, as we've established, dk->dk_kstats is NULL. Fix this by simply adding a NULL check before doing anything in dataset_kstats_rename. This still allows the dataset_name kstat value for the zvol to be updated (as was the intent of the original patch), and merely blocks attempts by the code to act upon the zvol's non-kstat-having snapshots. If at some future time, kstats are added for snapshots, then things should work as intended in that case as well. Signed-off-by: Justin Gottula <justin@jgottula.com>
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If a zvol is renamed, and it has one or more snapshots, and snapdev=visible is true for the zvol, then the rename causes a kernel null pointer dereference error. This has the effect (on Linux, anyway) of killing the z_zvol taskq kthread, with locks still held; which in turn causes a variety of zvol-related operations afterward to hang indefinitely (such as udev workers, among other things). The problem occurs because of an oversight in openzfs#15486 (e36ff84). As documented in dataset_kstats_create, some datasets may not actually have kstats allocated for them; and at least at the present time, this is true for snapshots. In practical terms, this means that for snapshots, dk->dk_kstats will be NULL. The dataset_kstats_rename function introduced in the patch above does not first check whether dk->dk_kstats is NULL before proceeding, unlike e.g. the nearby dataset_kstats_update_* functions. In the very particular circumstance in which a zvol is renamed, AND that zvol has one or more snapshots, AND that zvol also has snapdev=visible, zvol_rename_minors_impl will loop over not just the zvol dataset itself, but each of the zvol's snapshots as well, so that their device nodes will be renamed as well. This results in dataset_kstats_create being called for snapshots, where, as we've established, dk->dk_kstats is NULL. Fix this by simply adding a NULL check before doing anything in dataset_kstats_rename. This still allows the dataset_name kstat value for the zvol to be updated (as was the intent of the original patch), and merely blocks attempts by the code to act upon the zvol's non-kstat-having snapshots. If at some future time, kstats are added for snapshots, then things should work as intended in that case as well. Signed-off-by: Justin Gottula <justin@jgottula.com>
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jgottula
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Jul 14, 2024
If a zvol is renamed, and it has one or more snapshots, and snapdev=visible is true for the zvol, then the rename causes a kernel null pointer dereference error. This has the effect (on Linux, anyway) of killing the z_zvol taskq kthread, with locks still held; which in turn causes a variety of zvol-related operations afterward to hang indefinitely (such as udev workers, among other things). The problem occurs because of an oversight in openzfs#15486 (e36ff84). As documented in dataset_kstats_create, some datasets may not actually have kstats allocated for them; and at least at the present time, this is true for snapshots. In practical terms, this means that for snapshots, dk->dk_kstats will be NULL. The dataset_kstats_rename function introduced in the patch above does not first check whether dk->dk_kstats is NULL before proceeding, unlike e.g. the nearby dataset_kstats_update_* functions. In the very particular circumstance in which a zvol is renamed, AND that zvol has one or more snapshots, AND that zvol also has snapdev=visible, zvol_rename_minors_impl will loop over not just the zvol dataset itself, but each of the zvol's snapshots as well, so that their device nodes will be renamed as well. This results in dataset_kstats_create being called for snapshots, where, as we've established, dk->dk_kstats is NULL. Fix this by simply adding a NULL check before doing anything in dataset_kstats_rename. This still allows the dataset_name kstat value for the zvol to be updated (as was the intent of the original patch), and merely blocks attempts by the code to act upon the zvol's non-kstat-having snapshots. If at some future time, kstats are added for snapshots, then things should work as intended in that case as well. Signed-off-by: Justin Gottula <justin@jgottula.com>
tonyhutter
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Aug 15, 2024
#16316) If a zvol is renamed, and it has one or more snapshots, and snapdev=visible is true for the zvol, then the rename causes a kernel null pointer dereference error. This has the effect (on Linux, anyway) of killing the z_zvol taskq kthread, with locks still held; which in turn causes a variety of zvol-related operations afterward to hang indefinitely (such as udev workers, among other things). The problem occurs because of an oversight in #15486 (e36ff84). As documented in dataset_kstats_create, some datasets may not actually have kstats allocated for them; and at least at the present time, this is true for snapshots. In practical terms, this means that for snapshots, dk->dk_kstats will be NULL. The dataset_kstats_rename function introduced in the patch above does not first check whether dk->dk_kstats is NULL before proceeding, unlike e.g. the nearby dataset_kstats_update_* functions. In the very particular circumstance in which a zvol is renamed, AND that zvol has one or more snapshots, AND that zvol also has snapdev=visible, zvol_rename_minors_impl will loop over not just the zvol dataset itself, but each of the zvol's snapshots as well, so that their device nodes will be renamed as well. This results in dataset_kstats_create being called for snapshots, where, as we've established, dk->dk_kstats is NULL. Fix this by simply adding a NULL check before doing anything in dataset_kstats_rename. This still allows the dataset_name kstat value for the zvol to be updated (as was the intent of the original patch), and merely blocks attempts by the code to act upon the zvol's non-kstat-having snapshots. If at some future time, kstats are added for snapshots, then things should work as intended in that case as well. Signed-off-by: Justin Gottula <justin@jgottula.com> Reviewed-by: Rob Norris <robn@despairlabs.com> Reviewed-by: Alexander Motin <mav@FreeBSD.org> Reviewed-by: Alan Somers <asomers@gmail.com> Reviewed-by: Allan Jude <allan@klarasystems.com> Reviewed-by: Tony Hutter <hutter2@llnl.gov>
lundman
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Sep 4, 2024
openzfs#16316) If a zvol is renamed, and it has one or more snapshots, and snapdev=visible is true for the zvol, then the rename causes a kernel null pointer dereference error. This has the effect (on Linux, anyway) of killing the z_zvol taskq kthread, with locks still held; which in turn causes a variety of zvol-related operations afterward to hang indefinitely (such as udev workers, among other things). The problem occurs because of an oversight in openzfs#15486 (e36ff84). As documented in dataset_kstats_create, some datasets may not actually have kstats allocated for them; and at least at the present time, this is true for snapshots. In practical terms, this means that for snapshots, dk->dk_kstats will be NULL. The dataset_kstats_rename function introduced in the patch above does not first check whether dk->dk_kstats is NULL before proceeding, unlike e.g. the nearby dataset_kstats_update_* functions. In the very particular circumstance in which a zvol is renamed, AND that zvol has one or more snapshots, AND that zvol also has snapdev=visible, zvol_rename_minors_impl will loop over not just the zvol dataset itself, but each of the zvol's snapshots as well, so that their device nodes will be renamed as well. This results in dataset_kstats_create being called for snapshots, where, as we've established, dk->dk_kstats is NULL. Fix this by simply adding a NULL check before doing anything in dataset_kstats_rename. This still allows the dataset_name kstat value for the zvol to be updated (as was the intent of the original patch), and merely blocks attempts by the code to act upon the zvol's non-kstat-having snapshots. If at some future time, kstats are added for snapshots, then things should work as intended in that case as well. Signed-off-by: Justin Gottula <justin@jgottula.com> Reviewed-by: Rob Norris <robn@despairlabs.com> Reviewed-by: Alexander Motin <mav@FreeBSD.org> Reviewed-by: Alan Somers <asomers@gmail.com> Reviewed-by: Allan Jude <allan@klarasystems.com> Reviewed-by: Tony Hutter <hutter2@llnl.gov>
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Closes #15482 (for FreeBSD only)
Sponsored-by: Axcient
Signed-off-by: Alan Somers asomers@gmail.com
Motivation and Context
Fixes #15482 . It updates the kstat's dataset_name field when renaming a zvol.
Description
Add a
dataset_kstats_renamefunction, and call it duringzvol_os_rename_minoron FreeBSD. Fixing the bug on Linux is left for future work.How Has This Been Tested?
Manually tested with the Steps to Reproduce given in the linked issue
Types of changes
Checklist:
Signed-off-by.