mirror_zfs/module
Rob Norris d323fbf49c FreeBSD: zfs_putpages: don't undirty pages until after write completes
In syncing mode, zfs_putpages() would put the entire range of pages onto
the ZIL, then return VM_PAGER_OK for each page to the kernel. However,
an associated zil_commit() or txg sync had not happened at this point,
so the write may not actually be on disk.

So, we rework that case to use a ZIL commit callback, and do the
post-write work of undirtying the page and signaling completion there.
We return VM_PAGER_PEND to the kernel instead so it knows that we will
take care of it.

The original version of this (238eab7dc1) copied the Linux model and did
the cleanup in a ZIL callback for both async and sync. This was a
mistake, as FreeBSD does not have a separate "busy for writeback" flag
like Linux which keeps the page usable. The full sbusy flag locks the
entire page out until the itx callback fires, which for async is after
txg sync, which could be literal seconds in the future.

For the async case, the data is already on the DMU and the in-memory
ZIL, which is sufficient for async writeback, so the old method of
logging it without a callback, undirtying the page and returning is more
than sufficient and reclaims that lost performance.

Sponsored-by: Klara, Inc.
Sponsored-by: Wasabi Technology, Inc.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Mark Johnston <markj@FreeBSD.org>
Signed-off-by: Rob Norris <rob.norris@klarasystems.com>
Closes #17533
2025-07-15 15:58:15 -07:00
..
avl SPDX: license tags: CDDL-1.0 2025-03-13 17:56:27 -07:00
icp Linux build: silence objtool warnings 2025-06-04 17:40:09 -07:00
lua SPDX: license tags: MIT 2025-03-13 17:56:54 -07:00
nvpair nvlist: Add nvlist_snprintf() and zfs_dbgmsg_nvlist() 2025-04-18 09:22:16 -04:00
os FreeBSD: zfs_putpages: don't undirty pages until after write completes 2025-07-15 15:58:15 -07:00
unicode SPDX: license tags: CDDL-1.0 2025-03-13 17:56:27 -07:00
zcommon Implement dynamic gang header sizes 2025-07-09 14:02:53 -07:00
zfs Implement dynamic gang header sizes 2025-07-09 14:02:53 -07:00
zstd SPDX: license tags: BSD-3-Clause OR GPL-2.0-only 2025-03-13 17:57:17 -07:00
.gitignore FreeBSD: Ignore symlink to i386 includes 2022-08-02 16:34:23 -07:00
Kbuild.in Linux build: always use objtool 2025-05-29 18:04:20 -07:00
Makefile.bsd freebsd: unbreak module/Makefile.bsd build on 15-CURRENT-arm64 2025-04-05 19:43:41 -04:00
Makefile.in objtool wrapper: use absolute path to call the wrapper 2025-07-14 15:10:02 -07:00