@@ -3255,6 +3255,8 @@ extern ssize_t generic_file_buffered_write_iter(struct kiocb *, struct iov_iter
loff_t, loff_t *, ssize_t);
extern ssize_t do_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos);
extern ssize_t do_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos);
+extern int generic_segment_checks(const struct iovec *iov,
+ unsigned long *nr_segs, size_t *count, int access_flags);
/* fs/block_dev.c */
extern ssize_t blkdev_aio_read(struct kiocb *, const struct iovec *,
@@ -1981,6 +1981,45 @@ success:
return size;
}
+/*
+ * Performs necessary checks before doing a write
+ * @iov: io vector request
+ * @nr_segs: number of segments in the iovec
+ * @count: number of bytes to write
+ * @access_flags: type of access: %VERIFY_READ or %VERIFY_WRITE
+ *
+ * Adjust number of segments and amount of bytes to write (nr_segs should be
+ * properly initialized first). Returns appropriate error code that caller
+ * should return or zero in case that write should be allowed.
+ */
+int generic_segment_checks(const struct iovec *iov,
+ unsigned long *nr_segs, size_t *count, int access_flags)
+{
+ unsigned long seg;
+ size_t cnt = 0;
+ for (seg = 0; seg < *nr_segs; seg++) {
+ const struct iovec *iv = &iov[seg];
+
+ /*
+ * If any segment has a negative length, or the cumulative
+ * length ever wraps negative then return -EINVAL.
+ */
+ cnt += iv->iov_len;
+ if (unlikely((ssize_t)(cnt|iv->iov_len) < 0))
+ return -EINVAL;
+ if (access_ok(access_flags, iv->iov_base, iv->iov_len))
+ continue;
+ if (seg == 0)
+ return -EFAULT;
+ *nr_segs = seg;
+ cnt -= iv->iov_len; /* This segment is no good */
+ break;
+ }
+ *count = cnt;
+ return 0;
+}
+EXPORT_SYMBOL(generic_segment_checks);
+
static int file_read_iter_actor(read_descriptor_t *desc, struct page *page,
unsigned long offset, unsigned long size)
{
The commit is pushed to "branch-rh7-3.10.0-1160.11.1.vz7.172.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git after rh7-3.10.0-1160.11.1.vz7.172.7 ------> commit eeb28e46662c0936389316fa6b8e70fb44b72ba9 Author: Konstantin Khorenko <khorenko@virtuozzo.com> Date: Wed Dec 30 13:27:30 2020 +0300 fs: Resurrect generic_segment_checks() This is a partial revert of a9ca9d715754 ("kill generic_segment_checks()"). The patch resurrects the function, but does not restore any call for it. Why this functiona is needed then? For zfs. VZ kernel does not have file_operations::read_iter()/write_iter() compatible with mainstream version thus zfs external module tries live without iters and assumes generic_segment_checks() exists. So keep the generic_segment_checks() specially for zfs. https://bugs.openvz.org/browse/OVZ-7243 Signed-off-by: Konstantin Khorenko <khorenko@virtuozzo.com> --- include/linux/fs.h | 2 ++ mm/filemap.c | 39 +++++++++++++++++++++++++++++++++++++++ 2 files changed, 41 insertions(+)