Add FALLOCATE operation

fallocate filesystem operation preallocates media space for the given file.
If fallocate returns success then any subsequent write to the given range
never fails with 'not enough space' error.

3 files changed, 48 insertions, 1 deletions

diff --git a/include/fuse.h b/include/fuse.h
index 36b168c..c657e67 100644
--- a/include/fuse.h
+++ b/include/fuse.h
@@ -575,6 +575,19 @@ struct fuse_operations {
 	 * Introduced in version 2.9
 	 */
 	int (*flock) (const char *, struct fuse_file_info *, int op);
+
+	/**
+	 * Allocates space for an open file
+	 *
+	 * This function ensures that required space is allocated for specified
+	 * file.  If this function returns success then any subsequent write
+	 * request to specified range is guaranteed not to fail because of lack
+	 * of space on the file system media.
+	 *
+	 * Introduced in version 2.9.1
+	 */
+	int (*fallocate) (const char *, int, off_t, off_t,
+			  struct fuse_file_info *);
 };
 
 /** Extra context that may be needed by some filesystems
@@ -870,6 +883,8 @@ int fuse_fs_ioctl(struct fuse_fs *fs, const char *path, int cmd, void *arg,
 int fuse_fs_poll(struct fuse_fs *fs, const char *path,
 		 struct fuse_file_info *fi, struct fuse_pollhandle *ph,
 		 unsigned *reventsp);
+int fuse_fs_fallocate(struct fuse_fs *fs, const char *path, int mode,
+		 off_t offset, off_t length, struct fuse_file_info *fi);
 void fuse_fs_init(struct fuse_fs *fs, struct fuse_conn_info *conn);
 void fuse_fs_destroy(struct fuse_fs *fs);
 
diff --git a/include/fuse_kernel.h b/include/fuse_kernel.h
index 1ce072c..c632b58 100644
--- a/include/fuse_kernel.h
+++ b/include/fuse_kernel.h
@@ -80,6 +80,9 @@
  * 7.18
  *  - add FUSE_IOCTL_DIR flag
  *  - add FUSE_NOTIFY_DELETE
+ *
+ * 7.19
+ *  - add FUSE_FALLOCATE
  */
 
 #ifndef _LINUX_FUSE_H
@@ -116,7 +119,7 @@
 #define FUSE_KERNEL_VERSION 7
 
 /** Minor version number of this interface */
-#define FUSE_KERNEL_MINOR_VERSION 18
+#define FUSE_KERNEL_MINOR_VERSION 19
 
 /** The node ID of the root inode */
 #define FUSE_ROOT_ID 1
@@ -309,6 +312,7 @@ enum fuse_opcode {
 	FUSE_POLL          = 40,
 	FUSE_NOTIFY_REPLY  = 41,
 	FUSE_BATCH_FORGET  = 42,
+	FUSE_FALLOCATE     = 43,
 
 	/* CUSE specific operations */
 	CUSE_INIT          = 4096,
@@ -602,6 +606,14 @@ struct fuse_notify_poll_wakeup_out {
 	__u64	kh;
 };
 
+struct fuse_fallocate_in {
+	__u64	fh;
+	__u64	offset;
+	__u64	length;
+	__u32	mode;
+	__u32	padding;
+};
+
 struct fuse_in_header {
 	__u32	len;
 	__u32	opcode;
diff --git a/include/fuse_lowlevel.h b/include/fuse_lowlevel.h
index 3ecc46e..2036717 100644
--- a/include/fuse_lowlevel.h
+++ b/include/fuse_lowlevel.h
@@ -996,6 +996,26 @@ struct fuse_lowlevel_ops {
 	 */
 	void (*flock) (fuse_req_t req, fuse_ino_t ino,
 		       struct fuse_file_info *fi, int op);
+
+	/**
+	 * Allocate requested space. If this function returns success then
+	 * subsequent writes to the specified range shall not fail due to the lack
+	 * of free space on the file system storage media.
+	 *
+	 * Introduced in version 2.9
+	 *
+	 * Valid replies:
+	 *   fuse_reply_err
+	 *
+	 * @param req request handle
+	 * @param ino the inode number
+	 * @param offset starting point for allocated region
+	 * @param length size of allocated region
+	 * @param mode determines the operation to be performed on the given range,
+	 *             see fallocate(2)
+	 */
+	void (*fallocate) (fuse_req_t req, fuse_ino_t ino, int mode,
+		       off_t offset, off_t length, struct fuse_file_info *fi);
 };
 
 /**