fsdax: Fix infinite loop in dax_iomap_rw()
[ Upstream commit 17d9c15c ] 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: <TASK> 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: ca289e0b ("fsdax: switch dax_iomap_rw to use iomap_iter") Signed-off-by:Li Jinlin <lijinlin3@huawei.com> Reviewed-by:
Darrick J. Wong <djwong@kernel.org> Link: https://lore.kernel.org/r/20220725032050.3873372-1-lijinlin3@huawei.com Signed-off-by:
Dan Williams <dan.j.williams@intel.com> Signed-off-by:
Sasha Levin <sashal@kernel.org>
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9aac3819
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