fallocate should be a file operation

Currently all filesystems except XFS implement fallocate asynchronously,
while XFS forced a commit.  Both of these are suboptimal - in case of O_SYNC
I/O we really want our allocation on disk, especially for the !KEEP_SIZE
case where we actually grow the file with user-visible zeroes.  On the
other hand always commiting the transaction is a bad idea for fast-path
uses of fallocate like for example in recent Samba versions.   Given
that block allocation is a data plane operation anyway change it from
an inode operation to a file operation so that we have the file structure
available that lets us check for O_SYNC.

This also includes moving the code around for a few of the filesystems,
and remove the already unnedded S_ISDIR checks given that we only wire
up fallocate for regular files.

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

1 files changed, 2 insertions, 2 deletions

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 177b4ddea418..09b5bd6a7c6b 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1552,6 +1552,8 @@ struct file_operations {
         ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, loff_t *, size_t, unsigned int);
         ssize_t (*splice_read)(struct file *, loff_t *, struct pipe_inode_info *, size_t, unsigned int);
         int (*setlease)(struct file *, long, struct file_lock **);
+        long (*fallocate)(struct file *file, int mode, loff_t offset,
+                          loff_t len);
 };
 
 #define IPERM_FLAG_RCU  0x0001
@@ -1582,8 +1584,6 @@ struct inode_operations {
         ssize_t (*listxattr) (struct dentry *, char *, size_t);
         int (*removexattr) (struct dentry *, const char *);
         void (*truncate_range)(struct inode *, loff_t, loff_t);
-        long (*fallocate)(struct inode *inode, int mode, loff_t offset,
-                          loff_t len);
         int (*fiemap)(struct inode *, struct fiemap_extent_info *, u64 start,
                       u64 len);
 } ____cacheline_aligned;