8 files changed, 25 insertions, 68 deletions

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 4205ba752d40..89da56a58b63 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -2425,20 +2425,7 @@ static loff_t btrfs_file_llseek(struct file *file, loff_t offset, int whence)
                 }
         }
 
-        if (offset < 0 && !(file->f_mode & FMODE_UNSIGNED_OFFSET)) {
-                offset = -EINVAL;
-                goto out;
-        }
-        if (offset > inode->i_sb->s_maxbytes) {
-                offset = -EINVAL;
-                goto out;
-        }
-
-        /* Special lock needed here? */
-        if (offset != file->f_pos) {
-                file->f_pos = offset;
-                file->f_version = 0;
-        }
+        offset = vfs_setpos(file, offset, inode->i_sb->s_maxbytes);
 out:
         mutex_unlock(&inode->i_mutex);
         return offset;
diff --git a/fs/ceph/file.c b/fs/ceph/file.c
index 656e16907430..16c989d3e23c 100644
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -866,16 +866,7 @@ static loff_t ceph_llseek(struct file *file, loff_t offset, int whence)
                 break;
         }
 
-        if (offset < 0 || offset > inode->i_sb->s_maxbytes) {
-                offset = -EINVAL;
-                goto out;
-        }
-
-        /* Special lock needed here? */
-        if (offset != file->f_pos) {
-                file->f_pos = offset;
-                file->f_version = 0;
-        }
+        offset = vfs_setpos(file, offset, inode->i_sb->s_maxbytes);
 
 out:
         mutex_unlock(&inode->i_mutex);
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index b1b4d51b5d86..469361dbe619 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -494,17 +494,7 @@ static loff_t ext4_seek_data(struct file *file, loff_t offset, loff_t maxsize)
         if (dataoff > isize)
                 return -ENXIO;
 
-        if (dataoff < 0 && !(file->f_mode & FMODE_UNSIGNED_OFFSET))
-                return -EINVAL;
-        if (dataoff > maxsize)
-                return -EINVAL;
-
-        if (dataoff != file->f_pos) {
-                file->f_pos = dataoff;
-                file->f_version = 0;
-        }
-
-        return dataoff;
+        return vfs_setpos(file, dataoff, maxsize);
 }
 
 /*
@@ -580,17 +570,7 @@ static loff_t ext4_seek_hole(struct file *file, loff_t offset, loff_t maxsize)
         if (holeoff > isize)
                 holeoff = isize;
 
-        if (holeoff < 0 && !(file->f_mode & FMODE_UNSIGNED_OFFSET))
-                return -EINVAL;
-        if (holeoff > maxsize)
-                return -EINVAL;
-
-        if (holeoff != file->f_pos) {
-                file->f_pos = holeoff;
-                file->f_version = 0;
-        }
-
-        return holeoff;
+        return vfs_setpos(file, holeoff, maxsize);
 }
 
 /*
diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index 8a38714f1d92..41000f223ca4 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -2646,17 +2646,7 @@ static loff_t ocfs2_file_llseek(struct file *file, loff_t offset, int whence)
                 goto out;
         }
 
-        if (offset < 0 && !(file->f_mode & FMODE_UNSIGNED_OFFSET))
-                ret = -EINVAL;
-        if (!ret && offset > inode->i_sb->s_maxbytes)
-                ret = -EINVAL;
-        if (ret)
-                goto out;
-
-        if (offset != file->f_pos) {
-                file->f_pos = offset;
-                file->f_version = 0;
-        }
+        offset = vfs_setpos(file, offset, inode->i_sb->s_maxbytes);
 
 out:
         mutex_unlock(&inode->i_mutex);
diff --git a/fs/read_write.c b/fs/read_write.c
index 37d16e82b575..122a3846d9e1 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -41,7 +41,19 @@ static inline int unsigned_offsets(struct file *file)
         return file->f_mode & FMODE_UNSIGNED_OFFSET;
 }
 
-static loff_t lseek_execute(struct file *file, loff_t offset, loff_t maxsize)
+/**
+ * vfs_setpos - update the file offset for lseek
+ * @file:       file structure in question
+ * @offset:     file offset to seek to
+ * @maxsize:    maximum file size
+ *
+ * This is a low-level filesystem helper for updating the file offset to
+ * the value specified by @offset if the given offset is valid and it is
+ * not equal to the current file offset.
+ *
+ * Return the specified offset on success and -EINVAL on invalid offset.
+ */
+loff_t vfs_setpos(struct file *file, loff_t offset, loff_t maxsize)
 {
         if (offset < 0 && !unsigned_offsets(file))
                 return -EINVAL;
@@ -54,6 +66,7 @@ static loff_t lseek_execute(struct file *file, loff_t offset, loff_t maxsize)
         }
         return offset;
 }
+EXPORT_SYMBOL(vfs_setpos);
 
 /**
  * generic_file_llseek_size - generic llseek implementation for regular files
@@ -94,7 +107,7 @@ generic_file_llseek_size(struct file *file, loff_t offset, int whence,
                  * like SEEK_SET.
                  */
                 spin_lock(&file->f_lock);
-                offset = lseek_execute(file, file->f_pos + offset, maxsize);
+                offset = vfs_setpos(file, file->f_pos + offset, maxsize);
                 spin_unlock(&file->f_lock);
                 return offset;
         case SEEK_DATA:
@@ -116,7 +129,7 @@ generic_file_llseek_size(struct file *file, loff_t offset, int whence,
                 break;
         }
 
-        return lseek_execute(file, offset, maxsize);
+        return vfs_setpos(file, offset, maxsize);
 }
 EXPORT_SYMBOL(generic_file_llseek_size);
 
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 0ad2b95fca12..de3dc98f4e8f 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -1268,8 +1268,7 @@ xfs_seek_data(
         }
 
 out:
-        if (offset != file->f_pos)
-                file->f_pos = offset;
+        offset = vfs_setpos(file, offset, inode->i_sb->s_maxbytes);
 
 out_unlock:
         xfs_iunlock_map_shared(ip, lock);
@@ -1377,8 +1376,7 @@ out:
          * situation in particular.
          */
         offset = min_t(loff_t, offset, isize);
-        if (offset != file->f_pos)
-                file->f_pos = offset;
+        offset = vfs_setpos(file, offset, inode->i_sb->s_maxbytes);
 
 out_unlock:
         xfs_iunlock_map_shared(ip, lock);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index a137a73fc1fe..bccb1924ec93 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2426,6 +2426,7 @@ extern void
 file_ra_state_init(struct file_ra_state *ra, struct address_space *mapping);
 extern loff_t noop_llseek(struct file *file, loff_t offset, int whence);
 extern loff_t no_llseek(struct file *file, loff_t offset, int whence);
+extern loff_t vfs_setpos(struct file *file, loff_t offset, loff_t maxsize);
 extern loff_t generic_file_llseek(struct file *file, loff_t offset, int whence);
 extern loff_t generic_file_llseek_size(struct file *file, loff_t offset,
                 int whence, loff_t maxsize, loff_t eof);
diff --git a/mm/shmem.c b/mm/shmem.c
index f887358dabc5..118dfa4952f4 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1798,10 +1798,7 @@ static loff_t shmem_file_llseek(struct file *file, loff_t offset, int whence)
                 }
         }
 
-        if (offset >= 0 && offset != file->f_pos) {
-                file->f_pos = offset;
-                file->f_version = 0;
-        }
+        offset = vfs_setpos(file, offset, MAX_LFS_FILESIZE);
         mutex_unlock(&inode->i_mutex);
         return offset;
 }