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authorAmir Goldstein <amir73il@gmail.com>2022-06-30 22:58:49 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2022-06-30 15:16:38 -0700
commit868f9f2f8e004bfe0d3935b1976f625b2924893b (patch)
tree679e7b6269eb3394aba174df42dcd9cb1b685e24 /fs/ksmbd/smb2pdu.c
parent1a0e93df1e107dc766fdf86ae88076efd9f376e6 (diff)
vfs: fix copy_file_range() regression in cross-fs copies
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 <drinkcat@chromium.org> Reported-by: kernel test robot <oliver.sang@intel.com> Signed-off-by: Luis Henriques <lhenriques@suse.de> 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 <zhe.he@windriver.com> Tested-by: Namjae Jeon <linkinjeon@kernel.org> Tested-by: Luis Henriques <lhenriques@suse.de> Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/ksmbd/smb2pdu.c')
-rw-r--r--fs/ksmbd/smb2pdu.c16
1 files changed, 13 insertions, 3 deletions
diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c
index 94ab1dcd80e7..353f047e783c 100644
--- a/fs/ksmbd/smb2pdu.c
+++ b/fs/ksmbd/smb2pdu.c
@@ -7810,14 +7810,24 @@ int smb2_ioctl(struct ksmbd_work *work)
src_off = le64_to_cpu(dup_ext->SourceFileOffset);
dst_off = le64_to_cpu(dup_ext->TargetFileOffset);
length = le64_to_cpu(dup_ext->ByteCount);
- cloned = vfs_clone_file_range(fp_in->filp, src_off, fp_out->filp,
- dst_off, length, 0);
+ /*
+ * XXX: It is not clear if FSCTL_DUPLICATE_EXTENTS_TO_FILE
+ * should fall back to vfs_copy_file_range(). This could be
+ * beneficial when re-exporting nfs/smb mount, but note that
+ * this can result in partial copy that returns an error status.
+ * If/when FSCTL_DUPLICATE_EXTENTS_TO_FILE_EX is implemented,
+ * fall back to vfs_copy_file_range(), should be avoided when
+ * the flag DUPLICATE_EXTENTS_DATA_EX_SOURCE_ATOMIC is set.
+ */
+ cloned = vfs_clone_file_range(fp_in->filp, src_off,
+ fp_out->filp, dst_off, length, 0);
if (cloned == -EXDEV || cloned == -EOPNOTSUPP) {
ret = -EOPNOTSUPP;
goto dup_ext_out;
} else if (cloned != length) {
cloned = vfs_copy_file_range(fp_in->filp, src_off,
- fp_out->filp, dst_off, length, 0);
+ fp_out->filp, dst_off,
+ length, 0);
if (cloned != length) {
if (cloned < 0)
ret = cloned;