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, 1 insertions, 2 deletions

diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index 651d5237c155..4471a416c274 100644
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -60,7 +60,6 @@ ata *);
         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);
 
 locking rules:
@@ -88,7 +87,6 @@ getxattr:	no
 listxattr:      no
 removexattr:    yes
 truncate_range: yes
-fallocate:      no
 fiemap:         no
         Additionally, ->rmdir(), ->unlink() and ->rename() have ->i_mutex on
 victim.
@@ -437,6 +435,7 @@ prototypes:
         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 *, int, loff_t, loff_t);
 };
 
 locking rules: