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docs: update kernel bugs list for 2022-07-29

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* RAID1 device count problems fixed
 * log tree replay parent transid verify failure in 5.18 and 5.19 added, patches available but not upstream yet
 * flushoncommit issues fixed, discussion section removed
 * LOGICAL_INO vs dedupe hang added

Signed-off-by: Zygo Blaxell <bees@furryterror.org>
This commit is contained in:
Zygo Blaxell 2022-07-29 22:01:04 -04:00
parent a52062822a
commit 5f3cb9b374
1 changed files with 14 additions and 24 deletions
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38
docs/btrfs-kernel.md
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@ -9,7 +9,7 @@ This issue is fixed in kernel 5.4.14 and later.
**Recommended kernel versions for bees are 4.19, 5.4, 5.10, 5.11, or 5.12, **Recommended kernel versions for bees are 4.19, 5.4, 5.10, 5.11, or 5.12,
with recent LTS and -stable updates.** The latest released kernel as with recent LTS and -stable updates.** The latest released kernel as
of this writing is 5.12.3. of this writing is 5.18.15.
4.14, 4.9, and 4.4 LTS kernels with recent updates are OK with 4.14, 4.9, and 4.4 LTS kernels with recent updates are OK with
some issues. Older kernels will be slower (a little slower or a lot some issues. Older kernels will be slower (a little slower or a lot
@ -31,7 +31,7 @@ In some future bees release, this API version may become mandatory.
Kernel Bug Tracking Table Kernel Bug Tracking Table
------------------------- -------------------------
These bugs are particularly popular among bees users: These bugs are particularly popular among bees users, though not all are specifically relevant to bees:
| First bad kernel | Last bad kernel | Issue Description | Fixed Kernel Versions | Fix Commit | First bad kernel | Last bad kernel | Issue Description | Fixed Kernel Versions | Fix Commit
| :---: | :---: | --- | :---: | --- | :---: | :---: | --- | :---: | ---
@ -61,7 +61,11 @@ These bugs are particularly popular among bees users:
| 5.4 | 5.11 | spurious tree checker failures on extent ref hash | 5.11.5, 5.12 and later | 1119a72e223f btrfs: tree-checker: do not error out if extent ref hash doesn't match | 5.4 | 5.11 | spurious tree checker failures on extent ref hash | 5.11.5, 5.12 and later | 1119a72e223f btrfs: tree-checker: do not error out if extent ref hash doesn't match
| - | 5.11 | tree mod log issue #5 | 4.4.263, 4.9.263, 4.14.227, 4.19.183, 5.4.108, 5.10.26, 5.11.9, 5.12 and later | dbcc7d57bffc btrfs: fix race when cloning extent buffer during rewind of an old root | - | 5.11 | tree mod log issue #5 | 4.4.263, 4.9.263, 4.14.227, 4.19.183, 5.4.108, 5.10.26, 5.11.9, 5.12 and later | dbcc7d57bffc btrfs: fix race when cloning extent buffer during rewind of an old root
| - | 5.12 | tree mod log issue #6 | 4.14.233, 4.19.191, 5.4.118, 5.10.36, 5.11.20, 5.12.3, 5.13 and later | f9690f426b21 btrfs: fix race when picking most recent mod log operation for an old root | - | 5.12 | tree mod log issue #6 | 4.14.233, 4.19.191, 5.4.118, 5.10.36, 5.11.20, 5.12.3, 5.13 and later | f9690f426b21 btrfs: fix race when picking most recent mod log operation for an old root
| 4.15 | - | spurious warnings from `fs/fs-writeback.c` when `flushoncommit` is enabled | - | workaround: comment out the `WARN_ON` | 4.15 | 5.16 | spurious warnings from `fs/fs-writeback.c` when `flushoncommit` is enabled | 5.15.27, 5.16.13, 5.17 and later | a0f0cf8341e3 btrfs: get rid of warning on transaction commit when using flushoncommit
| - | 5.17 | crash during device removal can make filesystem unmountable | 5.15.54, 5.16.20, 5.17.3, 5.18 and later | bbac58698a55 btrfs: remove device item and update super block in the same transaction
| - | 5.18 | wrong superblock num_devices makes filesystem unmountable | 4.14.283, 4.19.247, 5.4.198, 5.10.121, 5.15.46, 5.17.14, 5.18.3 | d201238ccd2f btrfs: repair super block num_devices automatically
| 5.18 | 5.19 | parent transid verify failed during log tree replay after a crash during a rename operation | 5.20-rc1 and later | (not available upstream yet) btrfs: join running log transaction when logging new name
| 5.4 | - | kernel hang when multiple threads are running `LOGICAL_INO` and dedupe ioctl | - | workaround: reduce bees thread count to 1 with `-c1`
"Last bad kernel" refers to that version's last stable update from "Last bad kernel" refers to that version's last stable update from
kernel.org. Distro kernels may backport additional fixes. Consult kernel.org. Distro kernels may backport additional fixes. Consult
@ -77,7 +81,7 @@ A "-" for "first bad kernel" indicates the bug has been present since
the relevant feature first appeared in btrfs. the relevant feature first appeared in btrfs.
A "-" for "last bad kernel" indicates the bug has not yet been fixed as A "-" for "last bad kernel" indicates the bug has not yet been fixed as
of 5.8.14. of 5.18.15.
In cases where issues are fixed by commits spread out over multiple In cases where issues are fixed by commits spread out over multiple
kernel versions, "fixed kernel version" refers to the version that kernel versions, "fixed kernel version" refers to the version that
@ -87,6 +91,11 @@ contains all components of the fix.
Workarounds for known kernel bugs Workarounds for known kernel bugs
--------------------------------- ---------------------------------
* **Hangs with high worker thread counts**: On kernels newer than
5.4, multiple threads running `LOGICAL_INO` and dedupe ioctls
at the same time can lead to a kernel hang. The workaround is
to reduce the thread count to 1 with `-c1`.
* **Tree mod log issues**: bees will detect that a btrfs balance is * **Tree mod log issues**: bees will detect that a btrfs balance is
running, and pause bees activity until the balance is done. This avoids running, and pause bees activity until the balance is done. This avoids
running both the `LOGICAL_INO` ioctl and btrfs balance at the same time, running both the `LOGICAL_INO` ioctl and btrfs balance at the same time,
@ -128,7 +137,7 @@ Workarounds for known kernel bugs
Unfixed kernel bugs Unfixed kernel bugs
------------------- -------------------
As of 5.12.3: As of 5.18.15:
* **The kernel does not permit `btrfs send` and dedupe to run at the * **The kernel does not permit `btrfs send` and dedupe to run at the
same time**. Recent kernels no longer crash, but now refuse one same time**. Recent kernels no longer crash, but now refuse one
@ -151,22 +160,3 @@ As of 5.12.3:
still saves some IO. still saves some IO.
`btrfs receive` is not affected by this issue. `btrfs receive` is not affected by this issue.
* **Spurious warnings in `fs/fs-writeback.c`** on kernel 4.15 and later
when filesystem is mounted with `flushoncommit`. These
seem to be harmless (there are other locks which prevent
concurrent umount of the filesystem), but the underlying
problems that trigger the `WARN_ON` are [not trivial to
fix](https://www.spinics.net/lists/linux-btrfs/msg87752.html).
The warnings can be especially voluminous when bees is running.
Workarounds:
1. mount with `-o noflushoncommit`
2. patch kernel to remove warning in `fs/fs-writeback.c`.
Note that using kernels 4.14 and earlier is *not* a viable workaround
for this issue, because kernels 4.14 and earlier will eventually
deadlock when a filesystem is mounted with `-o flushoncommit` (a single
commit fixes one bug and introduces the other).