kernel/git/stable/linux-stable.git/fs/read_write.c, branch linux-5.18.y

fs: sendfile handles O_NONBLOCK of out_fd

2022-08-03T10:05:16+00:00

commit bdeb77bc2c405fa9f954c20269db175a0bd2793f upstream. sendfile has to return EAGAIN if out_fd is nonblocking and the write into it would block. Here is a small reproducer for the problem: #define _GNU_SOURCE /* See feature_test_macros(7) */ #include #include #include #include #include #include #include #define FILE_SIZE (1UL << 30) int main(int argc, char **argv) { int p[2], fd; if (pipe2(p, O_NONBLOCK)) return 1; fd = open(argv[1], O_RDWR | O_TMPFILE, 0666); if (fd < 0) return 1; ftruncate(fd, FILE_SIZE); if (sendfile(p[1], fd, 0, FILE_SIZE) == -1) { fprintf(stderr, "FAIL\n"); } if (sendfile(p[1], fd, 0, FILE_SIZE) != -1 || errno != EAGAIN) { fprintf(stderr, "FAIL\n"); } return 0; } It worked before b964bf53e540, it is stuck after b964bf53e540, and it works again with this fix. This regression occurred because do_splice_direct() calls pipe_write that handles O_NONBLOCK. Here is a trace log from the reproducer: 1) | __x64_sys_sendfile64() { 1) | do_sendfile() { 1) | __fdget() 1) | rw_verify_area() 1) | __fdget() 1) | rw_verify_area() 1) | do_splice_direct() { 1) | rw_verify_area() 1) | splice_direct_to_actor() { 1) | do_splice_to() { 1) | rw_verify_area() 1) | generic_file_splice_read() 1) + 74.153 us | } 1) | direct_splice_actor() { 1) | iter_file_splice_write() { 1) | __kmalloc() 1) 0.148 us | pipe_lock(); 1) 0.153 us | splice_from_pipe_next.part.0(); 1) 0.162 us | page_cache_pipe_buf_confirm(); ... 16 times 1) 0.159 us | page_cache_pipe_buf_confirm(); 1) | vfs_iter_write() { 1) | do_iter_write() { 1) | rw_verify_area() 1) | do_iter_readv_writev() { 1) | pipe_write() { 1) | mutex_lock() 1) 0.153 us | mutex_unlock(); 1) 1.368 us | } 1) 1.686 us | } 1) 5.798 us | } 1) 6.084 us | } 1) 0.174 us | kfree(); 1) 0.152 us | pipe_unlock(); 1) + 14.461 us | } 1) + 14.783 us | } 1) 0.164 us | page_cache_pipe_buf_release(); ... 16 times 1) 0.161 us | page_cache_pipe_buf_release(); 1) | touch_atime() 1) + 95.854 us | } 1) + 99.784 us | } 1) ! 107.393 us | } 1) ! 107.699 us | } Link: https://lkml.kernel.org/r/20220415005015.525191-1-avagin@gmail.com Fixes: b964bf53e540 ("teach sendfile(2) to handle send-to-pipe directly") Signed-off-by: Andrei Vagin Cc: Al Viro Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

vfs: fix copy_file_range() regression in cross-fs copies

2022-07-07T15:54:52+00:00

commit 868f9f2f8e004bfe0d3935b1976f625b2924893b upstream. A regression has been reported by Nicolas Boichat, found while using the copy_file_range syscall to copy a tracefs file. Before commit 5dae222a5ff0 ("vfs: allow copy_file_range to copy across devices") the kernel would return -EXDEV to userspace when trying to copy a file across different filesystems. After this commit, the syscall doesn't fail anymore and instead returns zero (zero bytes copied), as this file's content is generated on-the-fly and thus reports a size of zero. Another regression has been reported by He Zhe - the assertion of WARN_ON_ONCE(ret == -EOPNOTSUPP) can be triggered from userspace when copying from a sysfs file whose read operation may return -EOPNOTSUPP. Since we do not have test coverage for copy_file_range() between any two types of filesystems, the best way to avoid these sort of issues in the future is for the kernel to be more picky about filesystems that are allowed to do copy_file_range(). This patch restores some cross-filesystem copy restrictions that existed prior to commit 5dae222a5ff0 ("vfs: allow copy_file_range to copy across devices"), namely, cross-sb copy is not allowed for filesystems that do not implement ->copy_file_range(). Filesystems that do implement ->copy_file_range() have full control of the result - if this method returns an error, the error is returned to the user. Before this change this was only true for fs that did not implement the ->remap_file_range() operation (i.e. nfsv3). Filesystems that do not implement ->copy_file_range() still fall-back to the generic_copy_file_range() implementation when the copy is within the same sb. This helps the kernel can maintain a more consistent story about which filesystems support copy_file_range(). nfsd and ksmbd servers are modified to fall-back to the generic_copy_file_range() implementation in case vfs_copy_file_range() fails with -EOPNOTSUPP or -EXDEV, which preserves behavior of server-side-copy. fall-back to generic_copy_file_range() is not implemented for the smb operation FSCTL_DUPLICATE_EXTENTS_TO_FILE, which is arguably a correct change of behavior. Fixes: 5dae222a5ff0 ("vfs: allow copy_file_range to copy across devices") Link: https://lore.kernel.org/linux-fsdevel/20210212044405.4120619-1-drinkcat@chromium.org/ Link: https://lore.kernel.org/linux-fsdevel/CANMq1KDZuxir2LM5jOTm0xx+BnvW=ZmpsG47CyHFJwnw7zSX6Q@mail.gmail.com/ Link: https://lore.kernel.org/linux-fsdevel/20210126135012.1.If45b7cdc3ff707bc1efa17f5366057d60603c45f@changeid/ Link: https://lore.kernel.org/linux-fsdevel/20210630161320.29006-1-lhenriques@suse.de/ Reported-by: Nicolas Boichat Reported-by: kernel test robot Signed-off-by: Luis Henriques Fixes: 64bf5ff58dff ("vfs: no fallback for ->copy_file_range") Link: https://lore.kernel.org/linux-fsdevel/20f17f64-88cb-4e80-07c1-85cb96c83619@windriver.com/ Reported-by: He Zhe Tested-by: Namjae Jeon Tested-by: Luis Henriques Signed-off-by: Amir Goldstein Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2022-04-02T02:57:03+00:00

Pull vfs updates from Al Viro: "Assorted bits and pieces" * 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: aio: drop needless assignment in aio_read() clean overflow checks in count_mounts() a bit seq_file: fix NULL pointer arithmetic warning uml/x86: use x86 load_unaligned_zeropad() asm/user.h: killed unused macros constify struct path argument of finish_automount()/do_add_mount() fs: Remove FIXME comment in generic_write_checks()

fs: export variant of generic_write_checks without iov_iter

2022-03-14T12:13:50+00:00

Encoded I/O in Btrfs needs to check a write with a given logical size without an iov_iter that matches that size (because the iov_iter we have is for the compressed data). So, factor out the parts of generic_write_check() that don't need an iov_iter into a new generic_write_checks_count() function and export that. Reviewed-by: Nikolay Borisov Signed-off-by: Omar Sandoval Reviewed-by: David Sterba Signed-off-by: David Sterba

fs: export rw_verify_area()

2022-03-14T12:13:50+00:00

I'm adding btrfs ioctls to read and write compressed data, and rather than duplicating the checks in rw_verify_area(), let's just export it. Reviewed-by: Josef Bacik Signed-off-by: Omar Sandoval Reviewed-by: David Sterba Signed-off-by: David Sterba

fs: Remove FIXME comment in generic_write_checks()

2022-01-30T19:34:55+00:00

This patch removes an unnecessary comment that had to do with block special files from `generic_write_checks()`. The comment, originally added in Linux v2.4.14.9, was to clarify that we only set `pos` to the file size when the file was opened with `O_APPEND` if the file wasn't a block special file. Prior to Linux v2.4, block special files had a different `write()` function which was unified into a generic `write()` function in Linux v2.4. This generic `write()` function called `generic_write_checks()`. For more details, see this earlier conversation: https://lore.kernel.org/linux-fsdevel/Yc4Czk5A+p5p2Y4W@mit.edu/ Currently, block special devices have their own `write_iter()` function and no longer share the same `generic_write_checks()`, therefore rendering the comment irrelevant. Signed-off-by: Tal Zussman Co-authored-by: Xijiao Li Co-authored-by: Hans Montero Suggested-by: Theodore Ts'o Signed-off-by: Al Viro

fs: remove leftover comments from mandatory locking removal

2021-10-26T16:20:50+00:00

Stragglers from commit f7e33bdbd6d1 ("fs: remove mandatory file locking support"). Signed-off-by: Jeff Layton

fs: clean up after mandatory file locking support removal

2021-08-24T11:52:45+00:00

Commit 3efee0567b4a ("fs: remove mandatory file locking support") removes some operations in functions rw_verify_area(). As these functions are now simplified, do some syntactic clean-up as follow-up to the removal as well, which was pointed out by compiler warnings and static analysis. No functional change. Signed-off-by: Lukas Bulwahn Signed-off-by: Jeff Layton

fs: remove mandatory file locking support

2021-08-23T10:15:36+00:00

We added CONFIG_MANDATORY_FILE_LOCKING in 2015, and soon after turned it off in Fedora and RHEL8. Several other distros have followed suit. I've heard of one problem in all that time: Someone migrated from an older distro that supported "-o mand" to one that didn't, and the host had a fstab entry with "mand" in it which broke on reboot. They didn't actually _use_ mandatory locking so they just removed the mount option and moved on. This patch rips out mandatory locking support wholesale from the kernel, along with the Kconfig option and the Documentation file. It also changes the mount code to ignore the "mand" mount option instead of erroring out, and to throw a big, ugly warning. Signed-off-by: Jeff Layton

teach sendfile(2) to handle send-to-pipe directly

2021-01-26T04:29:36+00:00

no point going through the intermediate pipe Signed-off-by: Al Viro