1 files changed, 68 insertions, 7 deletions

diff --git a/fs/open.c b/fs/open.c
index be6a457f4226..1d9e5e98bf4e 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -26,6 +26,7 @@
 #include <linux/syscalls.h>
 #include <linux/rcupdate.h>
 #include <linux/audit.h>
+#include <linux/falloc.h>
 
 int vfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 {
@@ -255,24 +256,26 @@ static long do_sys_truncate(const char __user * path, loff_t length)
 	if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
 		goto dput_and_out;
 
-	/*
-	 * Make sure that there are no leases.
-	 */
-	error = break_lease(inode, FMODE_WRITE);
+	error = get_write_access(inode);
 	if (error)
 		goto dput_and_out;
 
-	error = get_write_access(inode);
+	/*
+	 * Make sure that there are no leases.  get_write_access() protects
+	 * against the truncate racing with a lease-granting setlease().
+	 */
+	error = break_lease(inode, FMODE_WRITE);
 	if (error)
-		goto dput_and_out;
+		goto put_write_and_out;
 
 	error = locks_verify_truncate(inode, NULL, length);
 	if (!error) {
 		DQUOT_INIT(inode);
 		error = do_truncate(nd.dentry, length, 0, NULL);
 	}
-	put_write_access(inode);
 
+put_write_and_out:
+	put_write_access(inode);
 dput_and_out:
 	path_release(&nd);
 out:
@@ -352,6 +355,64 @@ asmlinkage long sys_ftruncate64(unsigned int fd, loff_t length)
 }
 #endif
 
+asmlinkage long sys_fallocate(int fd, int mode, loff_t offset, loff_t len)
+{
+	struct file *file;
+	struct inode *inode;
+	long ret = -EINVAL;
+
+	if (offset < 0 || len <= 0)
+		goto out;
+
+	/* Return error if mode is not supported */
+	ret = -EOPNOTSUPP;
+	if (mode && !(mode & FALLOC_FL_KEEP_SIZE))
+		goto out;
+
+	ret = -EBADF;
+	file = fget(fd);
+	if (!file)
+		goto out;
+	if (!(file->f_mode & FMODE_WRITE))
+		goto out_fput;
+	/*
+	 * Revalidate the write permissions, in case security policy has
+	 * changed since the files were opened.
+	 */
+	ret = security_file_permission(file, MAY_WRITE);
+	if (ret)
+		goto out_fput;
+
+	inode = file->f_path.dentry->d_inode;
+
+	ret = -ESPIPE;
+	if (S_ISFIFO(inode->i_mode))
+		goto out_fput;
+
+	ret = -ENODEV;
+	/*
+	 * Let individual file system decide if it supports preallocation
+	 * for directories or not.
+	 */
+	if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
+		goto out_fput;
+
+	ret = -EFBIG;
+	/* Check for wrap through zero too */
+	if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0))
+		goto out_fput;
+
+	if (inode->i_op && inode->i_op->fallocate)
+		ret = inode->i_op->fallocate(inode, mode, offset, len);
+	else
+		ret = -EOPNOTSUPP;
+
+out_fput:
+	fput(file);
+out:
+	return ret;
+}
+
 /*
  * access() needs to use the real uid/gid, not the effective uid/gid.
  * We do this by temporarily clearing all FS-related capabilities and