[PATCH] Implement fallocate

[David Chinner <dgc@xxxxxxx>]

XFS fallocate() callout.

Allocate the range requested as unwritten extents. Atomically
change the file size if requested.

Signed-off-by: Dave Chinner <dgc@xxxxxxx>
---
 fs/xfs/linux-2.6/xfs_iops.c |   45 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

Index: 2.6.x-xfs-new/fs/xfs/linux-2.6/xfs_iops.c
===================================================================
--- 2.6.x-xfs-new.orig/fs/xfs/linux-2.6/xfs_iops.c      2007-10-30 
10:18:59.061735503 +1100
+++ 2.6.x-xfs-new/fs/xfs/linux-2.6/xfs_iops.c   2007-10-30 10:19:26.498185998 
+1100
@@ -52,6 +52,7 @@
 #include <linux/xattr.h>
 #include <linux/namei.h>
 #include <linux/security.h>
+#include <linux/falloc.h>
 
 /*
  * Bring the atime in the XFS inode uptodate.
@@ -796,6 +797,49 @@ xfs_vn_removexattr(
        return namesp->attr_remove(vp, attr, xflags);
 }
 
+/*
+ * generic space allocation vector.
+ */
+STATIC long
+xfs_vn_fallocate(
+       struct inode    *inode,
+       int             mode,
+       loff_t          offset,
+       loff_t          len)
+{
+       long            error;
+       loff_t          new_size = 0;
+       xfs_flock64_t   bf;
+
+       /* preallocation on directories not yet supported */
+       error = -ENODEV;
+       if (S_ISDIR(inode->i_mode))
+               goto out_error;
+
+       bf.l_whence = 0;
+       bf.l_start = offset;
+       bf.l_len = len;
+
+       xfs_ilock(XFS_I(inode), XFS_IOLOCK_EXCL);
+       error = xfs_change_file_space(XFS_I(inode), XFS_IOC_RESVSP, &bf,
+                                               0, NULL, ATTR_NOLOCK);
+       if (!error && !(mode & FALLOC_FL_KEEP_SIZE) &&
+           offset + len > i_size_read(inode))
+               new_size = offset + len;
+
+       /* Change file size if needed */
+       if (new_size) {
+               bhv_vattr_t     va;
+
+               va.va_mask = XFS_AT_SIZE;
+               va.va_size = new_size;
+               error = xfs_setattr(XFS_I(inode), &va, ATTR_NOLOCK, NULL);
+       }
+
+       xfs_iunlock(XFS_I(inode), XFS_IOLOCK_EXCL);
+out_error:
+       return error;
+}
 
 const struct inode_operations xfs_inode_operations = {
        .permission             = xfs_vn_permission,
@@ -806,6 +850,7 @@ const struct inode_operations xfs_inode_
        .getxattr               = xfs_vn_getxattr,
        .listxattr              = xfs_vn_listxattr,
        .removexattr            = xfs_vn_removexattr,
+       .fallocate              = xfs_vn_fallocate,
 };
 
 const struct inode_operations xfs_dir_inode_operations = {