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[ Upstream commitf70681e9e6] There is an issue in the kernel: In tmpfs, when using the "ls" command to list the contents of a directory with a large number of files, glibc performs the getdents call in multiple rounds. If a concurrent unlink occurs between these getdents calls, it may lead to duplicate directory entries in the ls output. One possible reproduction scenario is as follows: Create 1026 files and execute ls and rm concurrently: for i in {1..1026}; do echo "This is file $i" > /tmp/dir/file$i done ls /tmp/dir rm /tmp/dir/file4 ->getdents(file1026-file5) ->unlink(file4) ->getdents(file5,file3,file2,file1) It is expected that the second getdents call to return file3 through file1, but instead it returns an extra file5. The root cause of this problem is in the offset_dir_lookup function. It uses mas_find to determine the starting position for the current getdents call. Since mas_find locates the first position that is greater than or equal to mas->index, when file4 is deleted, it ends up returning file5. It can be fixed by replacing mas_find with mas_find_rev, which finds the first position that is less than or equal to mas->index. Fixes:b9b588f22a("libfs: Use d_children list to iterate simple_offset directories") Signed-off-by: Yongjian Sun <sunyongjian1@huawei.com> Link: https://lore.kernel.org/r/20250320034417.555810-1-sunyongjian@huaweicloud.com Reviewed-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
2261 lines
59 KiB
2261 lines
59 KiB