[PATCH v8 1/11] fs: Add support FALLOC_FL_INSERT_RANGE for fallocate

Namjae Jeon
2015-01-13T16:05:49Z

FALLOC_FL_INSERT_RANGE command is the opposite command of
FALLOC_FL_COLLAPSE_RANGE that is needed for advertisers or someone who want 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. and this command also has same limitation as FALLOC_FL_COLLAPSE_RANGE,
that is block boundary and use ftruncate(2) for crosses EOF.

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Ashish Sangwan <a.sangwan@samsung.com>
Cc: Brian Foster<bfoster@redhat.com>
---
fs/open.c | 8 +++++++-
include/uapi/linux/falloc.h | 17 +++++++++++++++++
2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/fs/open.c b/fs/open.c
index 813be03..762fb45 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -232,7 +232,8 @@ int vfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len)

/* 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))
+ FALLOC_FL_COLLAPSE_RANGE | FALLOC_FL_ZERO_RANGE |
+ FALLOC_FL_INSERT_RANGE))
return -EOPNOTSUPP;

/* Punch hole and zero range are mutually exclusive */
@@ -250,6 +251,11 @@ 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;

diff --git a/include/uapi/linux/falloc.h b/include/uapi/linux/falloc.h
index d1197ae..3e445a7 100644
--- a/include/uapi/linux/falloc.h
+++ b/include/uapi/linux/falloc.h
@@ -41,4 +41,21 @@
*/
#define FALLOC_FL_ZERO_RANGE 0x10

+/*
+ * FALLOC_FL_INSERT_RANGE is use to insert space within the file size without
+ * overwriting any existing data. The contents of the file beyond offset are
+ * shifted towards right by len bytes to create a hole. As such, this
+ * operation will increase the size of the file by len bytes.
+ *
+ * Different filesystems may implement different limitations on the granularity
+ * of the operation. Most will limit operations to filesystem block size
+ * boundaries, but this boundary may be larger or smaller depending on
+ * the filesystem and/or the configuration of the filesystem or file.
+ *
+ * Attempting to insert space using this flag at OR beyond the end of
+ * the file is considered an illegal operation - just use ftruncate(2) or
+ * fallocate(2) with mode 0 for such type of operations.
+ */
+#define FALLOC_FL_INSERT_RANGE 0x20
+
#endif /* _UAPI_FALLOC_H_ */
--
1.7.9.5