[XFS] Implement fallocate.

Implement the new generic callout for file preallocation. Atomically
change the file size if requested.

SGI-PV: 972756
SGI-Modid: xfs-linux-melb:xfs-kern:30009a

Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>

1 files changed, 43 insertions, 0 deletions

diff --git a/fs/xfs/linux-2.6/xfs_iops.c b/fs/xfs/linux-2.6/xfs_iops.c
index 264b1e7dacf7..9ddef91a436d 100644
--- a/fs/xfs/linux-2.6/xfs_iops.c
+++ b/fs/xfs/linux-2.6/xfs_iops.c
@@ -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.
@@ -794,6 +795,47 @@ xfs_vn_removexattr(
         return namesp->attr_remove(vp, attr, xflags);
 }
 
+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;
+        xfs_inode_t     *ip = XFS_I(inode);
+
+        /* 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(ip, XFS_IOLOCK_EXCL);
+        error = xfs_change_file_space(ip, 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(ip, &va, ATTR_NOLOCK, NULL);
+        }
+
+        xfs_iunlock(ip, XFS_IOLOCK_EXCL);
+out_error:
+        return error;
+}
 
 const struct inode_operations xfs_inode_operations = {
         .permission             = xfs_vn_permission,
@@ -804,6 +846,7 @@ const struct inode_operations xfs_inode_operations = {
         .getxattr               = xfs_vn_getxattr,
         .listxattr              = xfs_vn_listxattr,
         .removexattr            = xfs_vn_removexattr,
+        .fallocate              = xfs_vn_fallocate,
 };
 
 const struct inode_operations xfs_dir_inode_operations = {