kernel/linux.git/fs/dax.c, branch v5.15.208

dax: skip read lock assertion for read-only filesystems

2025-10-29T13:03:07+00:00

[ Upstream commit 154d1e7ad9e5ce4b2aaefd3862b3dba545ad978d ] The commit 168316db3583("dax: assert that i_rwsem is held exclusive for writes") added lock assertions to ensure proper locking in DAX operations. However, these assertions trigger false-positive lockdep warnings since read lock is unnecessary on read-only filesystems(e.g., erofs). This patch skips the read lock assertion for read-only filesystems, eliminating the spurious warnings while maintaining the integrity checks for writable filesystems. Fixes: 168316db3583 ("dax: assert that i_rwsem is held exclusive for writes") Signed-off-by: Yuezhang Mo Reviewed-by: Friendy Su Reviewed-by: Daniel Palmer Reviewed-by: Gao Xiang Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin

fsdax: Fix infinite loop in dax_iomap_rw()

2022-09-28T09:11:56+00:00

[ Upstream commit 17d9c15c9b9e7fb285f7ac5367dfb5f00ff575e3 ] I got an infinite loop and a WARNING report when executing a tail command in virtiofs. WARNING: CPU: 10 PID: 964 at fs/iomap/iter.c:34 iomap_iter+0x3a2/0x3d0 Modules linked in: CPU: 10 PID: 964 Comm: tail Not tainted 5.19.0-rc7 Call Trace: dax_iomap_rw+0xea/0x620 ? __this_cpu_preempt_check+0x13/0x20 fuse_dax_read_iter+0x47/0x80 fuse_file_read_iter+0xae/0xd0 new_sync_read+0xfe/0x180 ? 0xffffffff81000000 vfs_read+0x14d/0x1a0 ksys_read+0x6d/0xf0 __x64_sys_read+0x1a/0x20 do_syscall_64+0x3b/0x90 entry_SYSCALL_64_after_hwframe+0x63/0xcd The tail command will call read() with a count of 0. In this case, iomap_iter() will report this WARNING, and always return 1 which casuing the infinite loop in dax_iomap_rw(). Fixing by checking count whether is 0 in dax_iomap_rw(). Fixes: ca289e0b95af ("fsdax: switch dax_iomap_rw to use iomap_iter") Signed-off-by: Li Jinlin Reviewed-by: Darrick J. Wong Link: https://lore.kernel.org/r/20220725032050.3873372-1-lijinlin3@huawei.com Signed-off-by: Dan Williams Signed-off-by: Sasha Levin

dax: fix cache flush on PMD-mapped pages

2022-06-09T08:23:09+00:00

[ Upstream commit e583b5c472bd23d450e06f148dc1f37be74f7666 ] The flush_cache_page() only remove a PAGE_SIZE sized range from the cache. However, it does not cover the full pages in a THP except a head page. Replace it with flush_cache_range() to fix this issue. This is just a documentation issue with the respect to properly documenting the expected usage of cache flushing before modifying the pmd. However, in practice this is not a problem due to the fact that DAX is not available on architectures with virtually indexed caches per: commit d92576f1167c ("dax: does not work correctly with virtual aliasing caches") Link: https://lkml.kernel.org/r/20220403053957.10770-3-songmuchun@bytedance.com Fixes: f729c8c9b24f ("dax: wrprotect pmd_t in dax_mapping_entry_mkclean") Signed-off-by: Muchun Song Reviewed-by: Dan Williams Reviewed-by: Christoph Hellwig Cc: Alistair Popple Cc: Al Viro Cc: Hugh Dickins Cc: Jan Kara Cc: "Kirill A. Shutemov" Cc: Matthew Wilcox Cc: Ralph Campbell Cc: Ross Zwisler Cc: Xiongchun Duan Cc: Xiyu Yang Cc: Yang Shi Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin

Merge tag 'iomap-5.15-merge-4' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux

2021-08-31T18:13:35+00:00

Pull iomap updates from Darrick Wong: "The most notable externally visible change for this cycle is the addition of support for reads to inline tail fragments of files, which was requested by the erofs developers; and a correction for a kernel memory corruption bug if the sysadmin tries to activate a swapfile with more pages than the swapfile header suggests. We also now report writeback completion errors to the file mapping correctly, instead of munging all errors into EIO. Internally, the bulk of the changes are Christoph's patchset to reduce the indirect function call count by a third to a half by converting iomap iteration from a loop pattern to a generator/consumer pattern. As an added bonus, fsdax no longer open-codes iomap apply loops. Summary: - Simplify the bio_end_page usage in the buffered IO code. - Support reading inline data at nonzero offsets for erofs. - Fix some typos and bad grammar. - Convert kmap_atomic usage in the inline data read path. - Add some extra inline data input checking. - Fix a memory corruption bug stemming from iomap_swapfile_activate trying to activate more pages than mm was expecting. - Pass errnos through the page writeback code so that writeback errors are reported correctly instead of being munged to EIO. - Replace iomap_apply with a open-coded iterator loops to reduce the number of indirect calls by a third to a half. - Refactor the fsdax code to use iomap iterators instead of the open-coded iomap_apply code that it had before. - Format file range iomap tracepoint data in hexadecimal and standardize the names used in the pretty-print string" * tag 'iomap-5.15-merge-4' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux: (41 commits) iomap: standardize tracepoint formatting and storage mm/swap: consider max pages in iomap_swapfile_add_extent iomap: move loop control code to iter.c iomap: constify iomap_iter_srcmap fsdax: switch the fault handlers to use iomap_iter fsdax: factor out a dax_fault_actor() helper fsdax: factor out helpers to simplify the dax fault code iomap: rework unshare flag iomap: pass an iomap_iter to various buffered I/O helpers iomap: remove iomap_apply fsdax: switch dax_iomap_rw to use iomap_iter iomap: switch iomap_swapfile_activate to use iomap_iter iomap: switch iomap_seek_data to use iomap_iter iomap: switch iomap_seek_hole to use iomap_iter iomap: switch iomap_bmap to use iomap_iter iomap: switch iomap_fiemap to use iomap_iter iomap: switch __iomap_dio_rw to use iomap_iter iomap: switch iomap_page_mkwrite to use iomap_iter iomap: switch iomap_zero_range to use iomap_iter iomap: switch iomap_file_unshare to use iomap_iter ...

fsdax: switch the fault handlers to use iomap_iter

2021-08-17T04:26:33+00:00

Avoid the open coded calls to ->iomap_begin and ->iomap_end and call iomap_iter instead. Signed-off-by: Christoph Hellwig Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong

fsdax: factor out a dax_fault_actor() helper

2021-08-17T04:26:33+00:00

The core logic in the two dax page fault functions is similar. So, move the logic into a common helper function. Also, to facilitate the addition of new features, such as CoW, switch-case is no longer used to handle different iomap types. Signed-off-by: Shiyang Ruan Reviewed-by: Christoph Hellwig Reviewed-by: Ritesh Harjani Reviewed-by: Darrick J. Wong Signed-off-by: Christoph Hellwig Signed-off-by: Darrick J. Wong

fsdax: factor out helpers to simplify the dax fault code

2021-08-17T04:26:33+00:00

The dax page fault code is too long and a bit difficult to read. And it is hard to understand when we trying to add new features. Some of the PTE/PMD codes have similar logic. So, factor out helper functions to simplify the code. Signed-off-by: Shiyang Ruan Reviewed-by: Ritesh Harjani Reviewed-by: Darrick J. Wong [hch: minor cleanups] Signed-off-by: Christoph Hellwig Signed-off-by: Darrick J. Wong

fsdax: switch dax_iomap_rw to use iomap_iter

2021-08-17T04:26:33+00:00

Switch the dax_iomap_rw implementation to use iomap_iter. Signed-off-by: Christoph Hellwig Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong

fsdax: mark the iomap argument to dax_iomap_sector as const

2021-08-17T04:26:33+00:00

Signed-off-by: Christoph Hellwig Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong

Merge branch 'for-5.14/dax' into libnvdimm-fixes

2021-08-11T19:04:43+00:00

Pick up some small dax cleanups that make some of Ira's follow on work easier.