FUSE needs to selectively permit ->check_flags() on a per-file basis as it
does not support setting/unsetting O_DIRECT flag on an open file. Hence
passing 'struct file *' as a parameter to ->check_flags() is necessary to
inspect and compare file->f_flags with the new flags.
Signed-off-by: Anand Avati <[email protected]>
---
Documentation/filesystems/Locking | 2 +-
Documentation/filesystems/vfs.txt | 2 +-
fs/bad_inode.c | 2 +-
fs/fcntl.c | 2 +-
fs/nfs/file.c | 6 +++---
include/linux/fs.h | 2 +-
6 files changed, 8 insertions(+), 8 deletions(-)
diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index 57d827d..9619841 100644
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -426,7 +426,7 @@ prototypes:
loff_t *, int);
unsigned long (*get_unmapped_area)(struct file *, unsigned long,
unsigned long, unsigned long, unsigned long);
- int (*check_flags)(int);
+ int (*check_flags)(struct file *, int);
int (*flock) (struct file *, int, struct file_lock *);
ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, loff_t *,
size_t, unsigned int);
diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt
index 88b9f55..442aefb 100644
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -764,7 +764,7 @@ struct file_operations {
ssize_t (*sendfile) (struct file *, loff_t *, size_t, read_actor_t, void *);
ssize_t (*sendpage) (struct file *, struct page *, int, size_t, loff_t *, int);
unsigned long (*get_unmapped_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);
- int (*check_flags)(int);
+ int (*check_flags)(struct file *, int);
int (*flock) (struct file *, int, struct file_lock *);
ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, size_t, unsigned int);
ssize_t (*splice_read)(struct file *, struct pipe_inode_info *, size_t, unsigned int);
diff --git a/fs/bad_inode.c b/fs/bad_inode.c
index bfcb18f..c7eef18 100644
--- a/fs/bad_inode.c
+++ b/fs/bad_inode.c
@@ -120,7 +120,7 @@ static unsigned long bad_file_get_unmapped_area(struct file *file,
return -EIO;
}
-static int bad_file_check_flags(int flags)
+static int bad_file_check_flags(struct file *filp, int flags)
{
return -EIO;
}
diff --git a/fs/fcntl.c b/fs/fcntl.c
index 22764c7..1a2a6d3 100644
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -174,7 +174,7 @@ static int setfl(int fd, struct file * filp, unsigned long arg)
}
if (filp->f_op && filp->f_op->check_flags)
- error = filp->f_op->check_flags(arg);
+ error = filp->f_op->check_flags(filp, arg);
if (error)
return error;
diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 2f093ed..9f96a8b 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -56,7 +56,7 @@ static ssize_t nfs_file_write(struct kiocb *, const struct iovec *iov,
unsigned long nr_segs, loff_t pos);
static int nfs_file_flush(struct file *, fl_owner_t id);
static int nfs_file_fsync(struct file *, int datasync);
-static int nfs_check_flags(int flags);
+static int nfs_check_flags(struct file *, int flags);
static int nfs_lock(struct file *filp, int cmd, struct file_lock *fl);
static int nfs_flock(struct file *filp, int cmd, struct file_lock *fl);
static int nfs_setlease(struct file *file, long arg, struct file_lock **fl);
@@ -105,7 +105,7 @@ const struct inode_operations nfs3_file_inode_operations = {
# define IS_SWAPFILE(inode) (0)
#endif
-static int nfs_check_flags(int flags)
+static int nfs_check_flags(struct file *filp, int flags)
{
if ((flags & (O_APPEND | O_DIRECT)) == (O_APPEND | O_DIRECT))
return -EINVAL;
@@ -126,7 +126,7 @@ nfs_file_open(struct inode *inode, struct file *filp)
filp->f_path.dentry->d_name.name);
nfs_inc_stats(inode, NFSIOS_VFSOPEN);
- res = nfs_check_flags(filp->f_flags);
+ res = nfs_check_flags(filp, filp->f_flags);
if (res)
return res;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index b5b9792..98ce7c7 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1564,7 +1564,7 @@ struct file_operations {
int (*lock) (struct file *, int, struct file_lock *);
ssize_t (*sendpage) (struct file *, struct page *, int, size_t, loff_t *, int);
unsigned long (*get_unmapped_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);
- int (*check_flags)(int);
+ int (*check_flags)(struct file *, int);
int (*flock) (struct file *, int, struct file_lock *);
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);
--
1.7.4.4
On Wed, Jul 27, 2011 at 03:56:19AM -0700, Anand Avati wrote:
> FUSE currently disallows O_DIRECT flag in open(). It is tricky dealing with
> setting/unsetting of O_DIRECT flag on an open file. There are applications
> (primarily VMs and databases) which open files with O_DIRECT flag. These
> applications do not work on FUSE due to this limitation.
>
> The approach with this patch is to permit opens with O_DIRECT, but instead
> disable setting/unsetting of the O_DIRECT flag no matter how the file was
> opened. This limitation is for more practical than disallowing O_DIRECT
> altogether.
But it's also entirely incorrect. Fix your userspace to have a proper
fallback if O_DIRECT opens fail. It's a feature only supported by a few
filesystems, and very few operating systems.
FUSE currently disallows O_DIRECT flag in open(). It is tricky dealing with
setting/unsetting of O_DIRECT flag on an open file. There are applications
(primarily VMs and databases) which open files with O_DIRECT flag. These
applications do not work on FUSE due to this limitation.
The approach with this patch is to permit opens with O_DIRECT, but instead
disable setting/unsetting of the O_DIRECT flag no matter how the file was
opened. This limitation is for more practical than disallowing O_DIRECT
altogether.
Signed-off-by: Anand Avati <[email protected]>
---
fs/fuse/file.c | 36 ++++++++++++++++++++++++++++++++----
1 files changed, 32 insertions(+), 4 deletions(-)
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 82a6646..355c30f 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -154,6 +154,27 @@ int fuse_do_open(struct fuse_conn *fc, u64 nodeid, struct file *file,
return err;
}
+ if (file->f_flags & O_DIRECT) {
+ if (!(outarg.open_flags & FOPEN_DIRECT_IO)) {
+ /* filesystem process did not acknowledge the O_DIRECT
+ flag with FOPEN_DIRECT_IO bit in ourarg. Hence
+ we fail the open().
+
+ Notify the filesystem process about the failed
+ open with fuse_sync_release right here itself as
+ file->private_data is not yet set up for release
+ notification.
+ */
+ fuse_sync_release(ff, file->f_flags);
+ return -EINVAL;
+ }
+
+ /* make VFS believe we don't support O_DIRECT till we
+ implement a_ops->direct_IO
+ */
+ file->f_flags &= ~O_DIRECT;
+ }
+
if (isdir)
outarg.open_flags &= ~FOPEN_DIRECT_IO;
@@ -193,10 +214,6 @@ int fuse_open_common(struct inode *inode, struct file *file, bool isdir)
struct fuse_conn *fc = get_fuse_conn(inode);
int err;
- /* VFS checks this, but only _after_ ->open() */
- if (file->f_flags & O_DIRECT)
- return -EINVAL;
-
err = generic_file_open(inode, file);
if (err)
return err;
@@ -2132,6 +2149,15 @@ int fuse_notify_poll_wakeup(struct fuse_conn *fc,
return 0;
}
+
+static int fuse_check_flags(struct file *filp, int flags)
+{
+ if ((filp->f_flags ^ flags) & O_DIRECT)
+ return -EINVAL;
+ return 0;
+}
+
+
static const struct file_operations fuse_file_operations = {
.llseek = fuse_file_llseek,
.read = do_sync_read,
@@ -2149,6 +2175,7 @@ static const struct file_operations fuse_file_operations = {
.unlocked_ioctl = fuse_file_ioctl,
.compat_ioctl = fuse_file_compat_ioctl,
.poll = fuse_file_poll,
+ .check_flags = fuse_check_flags,
};
static const struct file_operations fuse_direct_io_file_operations = {
@@ -2165,6 +2192,7 @@ static const struct file_operations fuse_direct_io_file_operations = {
.unlocked_ioctl = fuse_file_ioctl,
.compat_ioctl = fuse_file_compat_ioctl,
.poll = fuse_file_poll,
+ .check_flags = fuse_check_flags,
/* no splice_read */
};
--
1.7.4.4