mirror_zfs/module/os/freebsd/zfs
Brian Atkinson b4e4cbeb20
Always validate checksums for Direct I/O reads
This fixes an oversight in the Direct I/O PR. There is nothing that
stops a process from manipulating the contents of a buffer for a
Direct I/O read while the I/O is in flight. This can lead checksum
verify failures. However, the disk contents are still correct, and this
would lead to false reporting of checksum validation failures.

To remedy this, all Direct I/O reads that have a checksum verification
failure are treated as suspicious. In the event a checksum validation
failure occurs for a Direct I/O read, then the I/O request will be
reissued though the ARC. This allows for actual validation to happen and
removes any possibility of the buffer being manipulated after the I/O
has been issued.

Just as with Direct I/O write checksum validation failures, Direct I/O
read checksum validation failures are reported though zpool status -d in
the DIO column. Also the zevent has been updated to have both:
1. dio_verify_wr -> Checksum verification failure for writes
2. dio_verify_rd -> Checksum verification failure for reads.
This allows for determining what I/O operation was the culprit for the
checksum verification failure. All DIO errors are reported only on the
top-level VDEV.

Even though FreeBSD can write protect pages (stable pages) it still has
the same issue as Linux with Direct I/O reads.

This commit updates the following:
1. Propogates checksum failures for reads all the way up to the
   top-level VDEV.
2. Reports errors through zpool status -d as DIO.
3. Has two zevents for checksum verify errors with Direct I/O. One for
   read and one for write.
4. Updates FreeBSD ABD code to also check for ABD_FLAG_FROM_PAGES and
   handle ABD buffer contents validation the same as Linux.
5. Updated manipulate_user_buffer.c to also manipulate a buffer while a
   Direct I/O read is taking place.
6. Adds a new ZTS test case dio_read_verify that stress tests the new
   code.
7. Updated man pages.
8. Added an IMPLY statement to zio_checksum_verify() to make sure that
   Direct I/O reads are not issued as speculative.
9. Removed self healing through mirror, raidz, and dRAID VDEVs for
   Direct I/O reads.

This issue was first observed when installing a Windows 11 VM on a ZFS
dataset with the dataset property direct set to always. The zpool
devices would report checksum failures, but running a subsequent zpool
scrub would not repair any data and report no errors.

Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Signed-off-by: Brian Atkinson <batkinson@lanl.gov>
Closes #16598
2024-10-09 12:28:08 -07:00
..
abd_os.c Always validate checksums for Direct I/O reads 2024-10-09 12:28:08 -07:00
arc_os.c FreeBSD: Add missing memory reclamation accounting 2024-08-05 09:21:29 -07:00
crypto_os.c FreeBSD: remove support for FreeBSD < 13.0-RELEASE (#16372) 2024-08-05 16:56:45 -07:00
dmu_os.c FreeBSD: remove support for FreeBSD < 13.0-RELEASE (#16372) 2024-08-05 16:56:45 -07:00
event_os.c FreeBSD: remove support for FreeBSD < 13.0-RELEASE (#16372) 2024-08-05 16:56:45 -07:00
hkdf.c Remove bcopy(), bzero(), bcmp() 2022-03-15 15:13:42 -07:00
kmod_core.c FreeBSD: remove support for FreeBSD < 13.0-RELEASE (#16372) 2024-08-05 16:56:45 -07:00
spa_os.c Fix build on FreeBSD 2023-03-22 09:24:41 -07:00
sysctl_os.c Remove unused sysctl node 2024-09-03 17:52:33 -07:00
vdev_file.c zfs_file: rename zfs_file_fallocate to zfs_file_deallocate 2024-09-18 11:35:04 -07:00
vdev_geom.c FreeBSD: remove support for FreeBSD < 13.0-RELEASE (#16372) 2024-08-05 16:56:45 -07:00
vdev_label_os.c Use abd_zero_off() where applicable 2023-11-17 13:28:32 -08:00
zfs_acl.c Fix an uninitialized data access (#16511) 2024-09-10 09:08:45 -07:00
zfs_ctldir.c FreeBSD: remove support for FreeBSD < 13.0-RELEASE (#16372) 2024-08-05 16:56:45 -07:00
zfs_debug.c zfs_debug: specific variant for userspace 2024-09-19 15:49:50 -07:00
zfs_dir.c Support for longnames for files/directories (Linux part) 2024-10-01 13:40:27 -07:00
zfs_file_os.c zfs_file: implement zfs_file_deallocate for FreeBSD 14 2024-09-18 11:35:48 -07:00
zfs_ioctl_compat.c freebsd: remove __FBSDID macro use 2023-11-17 14:02:09 -08:00
zfs_ioctl_os.c FreeBSD: remove support for FreeBSD < 13.0-RELEASE (#16372) 2024-08-05 16:56:45 -07:00
zfs_racct.c Adding Direct IO Support 2024-09-14 13:47:59 -07:00
zfs_vfsops.c Support for longnames for files/directories (Linux part) 2024-10-01 13:40:27 -07:00
zfs_vnops_os.c snapdir: add 'disabled' value to make .zfs inaccessible 2024-10-02 09:12:02 -07:00
zfs_znode_os.c Support for longnames for files/directories (Linux part) 2024-10-01 13:40:27 -07:00
zio_crypt.c ZIL: Assert record sizes in different places 2023-11-28 13:35:14 -08:00
zvol_os.c Adding Direct IO Support 2024-09-14 13:47:59 -07:00