zfs/module
Brian Behlendorf c7db374ac6 Fix buffered/direct/mmap I/O race
When a page is faulted in for memory mapped I/O the page lock
may be dropped before it has been read and marked up to date.
If a buffered read encounters such a page in mappedread() it
must wait until the page has been updated. Failure to do so
will result in a panic on debug builds and incorrect data on
production builds.

The critical part of this change is in mappedread() where pages
which are not up to date are now handled. Additionally, it
includes the following simplifications.

- zfs_getpage() and zfs_fillpage() could be passed an array of
  pages. This could be more efficient if it was used but in
  practice only a single page was ever provided. These
  interfaces were simplified to acknowledge that.

- update_pages() was modified to correctly set the PG_error bit
  on a page when it cannot be read by dmu_read().

- Setting PG_error and PG_uptodate was moved to zfs_fillpage()
  from zpl_readpage_common(). This is consistent with the
  handling in update_pages() and mappedread().

- Minor additional refactoring to comments and variable
  declarations to improve readability.

- Add a test case to exercise concurrent buffered, direct,
  and mmap IO to the same file.

- Reduce the mmap_sync test case default run time.

Reviewed-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Reviewed-by: Brian Atkinson <batkinson@lanl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #13608
Closes #14498
2023-04-21 13:12:35 -07:00
..
avl AVL: Remove obsolete branching optimizations 2022-07-26 10:10:37 -07:00
icp Fix possible NULL pointer dereference in sha2_mac_init() 2022-12-01 12:39:42 -08:00
lua Lua: Fix bad bitshift in lua_strx2number() 2022-12-01 12:39:44 -08:00
nvpair Update `checkstyle` workflow env to ubuntu-20.04 2021-12-08 13:27:56 -08:00
os Fix buffered/direct/mmap I/O race 2023-04-21 13:12:35 -07:00
spl Cleanup linux module kbuild files 2020-06-10 09:24:15 -07:00
unicode Illumos #15286: do_composition() needs sign awareness 2023-01-19 12:50:42 -08:00
zcommon dsl_prop_known_index(): check for invalid prop 2022-11-08 10:16:21 -08:00
zfs Revert "ZFS_IOC_COUNT_FILLED does unnecessary txg_wait_synced()" 2023-04-18 11:44:07 -07:00
zstd module: zstd: check we don't leak symbols; regenerate symbol map 2022-05-16 15:48:21 -07:00
.gitignore FreeBSD: Ignore symlink to i386 includes 2022-09-28 10:35:13 -07:00
Kbuild.in Add zstd support to zfs 2020-08-20 10:30:06 -07:00
Makefile.bsd FreeBSD: Silence clang unused-but-set-variable 2022-06-15 11:27:28 -07:00
Makefile.in Add support for $KERNEL_{CC,LD,LLVM} variables 2022-02-16 17:58:55 -08:00