fs: Add support FALLOC_FL_INSERT_RANGE for fallocate

FALLOC_FL_INSERT_RANGE command is the opposite command of
FALLOC_FL_COLLAPSE_RANGE that is needed for someone who wants to add
some data in the middle of file.

FALLOC_FL_INSERT_RANGE will create space for writing new data within
a file after shifting extents to right as given length. This command
also has same limitations as FALLOC_FL_COLLAPSE_RANGE in that
operations need to be filesystem block boundary aligned and cannot
cross the current EOF.

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Ashish Sangwan <a.sangwan@samsung.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

1 files changed, 6 insertions, 2 deletions

diff --git a/fs/open.c b/fs/open.c
index 33f9cbf2610b..b724cc0e0228 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -231,8 +231,7 @@ int vfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
                 return -EINVAL;
 
         /* Return error if mode is not supported */
-        if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE |
-                     FALLOC_FL_COLLAPSE_RANGE | FALLOC_FL_ZERO_RANGE))
+        if (mode & ~FALLOC_FL_SUPPORTED_MASK)
                 return -EOPNOTSUPP;
 
         /* Punch hole and zero range are mutually exclusive */
@@ -250,6 +249,11 @@ int vfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
             (mode & ~FALLOC_FL_COLLAPSE_RANGE))
                 return -EINVAL;
 
+        /* Insert range should only be used exclusively. */
+        if ((mode & FALLOC_FL_INSERT_RANGE) &&
+            (mode & ~FALLOC_FL_INSERT_RANGE))
+                return -EINVAL;
+
         if (!(file->f_mode & FMODE_WRITE))
                 return -EBADF;