mm: move common segment checks to separate helper function

[akpm@linux-foundation.org: cleanup]
Signed-off-by: Monakhov Dmitriy <dmonakhov@openvz.org>
Cc: Christoph Hellwig <hch@lst.de>
Acked-by: Anton Altaparmakov <aia21@cam.ac.uk>
Acked-by: David Chinner <dgc@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

4 files changed, 53 insertions, 74 deletions

diff --git a/fs/ntfs/file.c b/fs/ntfs/file.c
index dbbac5593106..621de369e6f8 100644
--- a/fs/ntfs/file.c
+++ b/fs/ntfs/file.c
@@ -2129,28 +2129,13 @@ static ssize_t ntfs_file_aio_write_nolock(struct kiocb *iocb,
         struct address_space *mapping = file->f_mapping;
         struct inode *inode = mapping->host;
         loff_t pos;
-        unsigned long seg;
         size_t count;           /* after file limit checks */
         ssize_t written, err;
 
         count = 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.
-                 */
-                count += iv->iov_len;
-                if (unlikely((ssize_t)(count|iv->iov_len) < 0))
-                        return -EINVAL;
-                if (access_ok(VERIFY_READ, iv->iov_base, iv->iov_len))
-                        continue;
-                if (!seg)
-                        return -EFAULT;
-                nr_segs = seg;
-                count -= iv->iov_len;   /* This segment is no good */
-                break;
-        }
+        err = generic_segment_checks(iov, &nr_segs, &count, VERIFY_READ);
+        if (err)
+                return err;
         pos = *ppos;
         vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
         /* We can write back this queue in page reclaim. */
diff --git a/fs/xfs/linux-2.6/xfs_lrw.c b/fs/xfs/linux-2.6/xfs_lrw.c
index ff8d64eba9f8..558076dd0752 100644
--- a/fs/xfs/linux-2.6/xfs_lrw.c
+++ b/fs/xfs/linux-2.6/xfs_lrw.c
@@ -639,7 +639,6 @@ xfs_write(
         xfs_fsize_t             isize, new_size;
         xfs_iocore_t            *io;
         bhv_vnode_t             *vp;
-        unsigned long           seg;
         int                     iolock;
         int                     eventsent = 0;
         bhv_vrwlock_t           locktype;
@@ -652,24 +651,9 @@ xfs_write(
         vp = BHV_TO_VNODE(bdp);
         xip = XFS_BHVTOI(bdp);
 
-        for (seg = 0; seg < segs; seg++) {
-                const struct iovec *iv = &iovp[seg];
-
-                /*
-                 * If any segment has a negative length, or the cumulative
-                 * length ever wraps negative then return -EINVAL.
-                 */
-                ocount += iv->iov_len;
-                if (unlikely((ssize_t)(ocount|iv->iov_len) < 0))
-                        return -EINVAL;
-                if (access_ok(VERIFY_READ, iv->iov_base, iv->iov_len))
-                        continue;
-                if (seg == 0)
-                        return -EFAULT;
-                segs = seg;
-                ocount -= iv->iov_len;  /* This segment is no good */
-                break;
-        }
+        error = generic_segment_checks(iovp, &segs, &ocount, VERIFY_READ);
+        if (error)
+                return error;
 
         count = ocount;
         pos = *offset;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index bc6d27cecaac..020a8426e10a 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1735,6 +1735,8 @@ extern ssize_t generic_file_sendfile(struct file *, loff_t *, size_t, read_actor
 extern void do_generic_mapping_read(struct address_space *mapping,
                                     struct file_ra_state *, struct file *,
                                     loff_t *, read_descriptor_t *, read_actor_t);
+extern int generic_segment_checks(const struct iovec *iov,
+                unsigned long *nr_segs, size_t *count, int access_flags);
 
 /* fs/splice.c */
 extern ssize_t generic_file_splice_read(struct file *, loff_t *,
diff --git a/mm/filemap.c b/mm/filemap.c
index 5631d6b2a62d..3e49fe13d6ac 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1110,6 +1110,45 @@ 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);
+
 /**
  * generic_file_aio_read - generic filesystem read routine
  * @iocb:       kernel I/O control block
@@ -1131,24 +1170,9 @@ generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
         loff_t *ppos = &iocb->ki_pos;
 
         count = 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.
-                 */
-                count += iv->iov_len;
-                if (unlikely((ssize_t)(count|iv->iov_len) < 0))
-                        return -EINVAL;
-                if (access_ok(VERIFY_WRITE, iv->iov_base, iv->iov_len))
-                        continue;
-                if (seg == 0)
-                        return -EFAULT;
-                nr_segs = seg;
-                count -= iv->iov_len;   /* This segment is no good */
-                break;
-        }
+        retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE);
+        if (retval)
+                return retval;
 
         /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
         if (filp->f_flags & O_DIRECT) {
@@ -2218,30 +2242,14 @@ __generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
         size_t ocount;          /* original count */
         size_t count;           /* after file limit checks */
         struct inode    *inode = mapping->host;
-        unsigned long   seg;
         loff_t          pos;
         ssize_t         written;
         ssize_t         err;
 
         ocount = 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.
-                 */
-                ocount += iv->iov_len;
-                if (unlikely((ssize_t)(ocount|iv->iov_len) < 0))
-                        return -EINVAL;
-                if (access_ok(VERIFY_READ, iv->iov_base, iv->iov_len))
-                        continue;
-                if (seg == 0)
-                        return -EFAULT;
-                nr_segs = seg;
-                ocount -= iv->iov_len;  /* This segment is no good */
-                break;
-        }
+        err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ);
+        if (err)
+                return err;
 
         count = ocount;
         pos = *ppos;