fs: Add new pre-allocation ioctls to vfs for compatibility with legacy xfs ioctls

This patch adds ioctls to vfs for compatibility with legacy XFS
pre-allocation ioctls (XFS_IOC_*RESVP*). The implementation
effectively invokes sys_fallocate for the new ioctls.
Also handles the compat_ioctl case.
Note: These legacy ioctls are also implemented by OCFS2.

[AV: folded fixes from hch]

Signed-off-by: Ankit Jain <me@ankitjain.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 35 insertions, 0 deletions

diff --git a/fs/ioctl.c b/fs/ioctl.c
index 001f8d3118f2..5612880fcbe7 100644
--- a/fs/ioctl.c
+++ b/fs/ioctl.c
@@ -15,6 +15,7 @@
 #include <linux/uaccess.h>
 #include <linux/writeback.h>
 #include <linux/buffer_head.h>
+#include <linux/falloc.h>
 
 #include <asm/ioctls.h>
 
@@ -403,6 +404,37 @@ EXPORT_SYMBOL(generic_block_fiemap);
 
 #endif  /*  CONFIG_BLOCK  */
 
+/*
+ * This provides compatibility with legacy XFS pre-allocation ioctls
+ * which predate the fallocate syscall.
+ *
+ * Only the l_start, l_len and l_whence fields of the 'struct space_resv'
+ * are used here, rest are ignored.
+ */
+int ioctl_preallocate(struct file *filp, void __user *argp)
+{
+        struct inode *inode = filp->f_path.dentry->d_inode;
+        struct space_resv sr;
+
+        if (copy_from_user(&sr, argp, sizeof(sr)))
+                return -EFAULT;
+
+        switch (sr.l_whence) {
+        case SEEK_SET:
+                break;
+        case SEEK_CUR:
+                sr.l_start += filp->f_pos;
+                break;
+        case SEEK_END:
+                sr.l_start += i_size_read(inode);
+                break;
+        default:
+                return -EINVAL;
+        }
+
+        return do_fallocate(filp, FALLOC_FL_KEEP_SIZE, sr.l_start, sr.l_len);
+}
+
 static int file_ioctl(struct file *filp, unsigned int cmd,
                 unsigned long arg)
 {
@@ -414,6 +446,9 @@ static int file_ioctl(struct file *filp, unsigned int cmd,
                 return ioctl_fibmap(filp, p);
         case FIONREAD:
                 return put_user(i_size_read(inode) - filp->f_pos, p);
+        case FS_IOC_RESVSP:
+        case FS_IOC_RESVSP64:
+                return ioctl_preallocate(filp, p);
         }
 
         return vfs_ioctl(filp, cmd, arg);