Implement ->direct_IO() method in aops. The ->direct_IO() method combines
the existing fuse_direct_read/fuse_direct_write methods to implement
O_DIRECT functionality.
Reaching ->direct_IO() in the read path via generic_file_aio_read ensures
proper synchronization with page cache with its existing framework.
Reaching ->direct_IO() in the write path via fuse_file_aio_write is made
to come via generic_file_direct_write() which makes it play nice with
the page cache w.r.t other mmap pages etc.
On files marked 'direct_io' by the filesystem server, IO always follows
the fuse_direct_read/write path. There is no effect of fcntl(O_DIRECT)
and it always succeeds.
On files not marked with 'direct_io' by the filesystem server, the IO
path depends on O_DIRECT flag by the application. This can be passed
at the time of open() as well as via fcntl().
Note that asynchronous O_DIRECT iocb jobs are completed synchronously
always (this has been the case with FUSE even before this patch)
Signed-off-by: Anand Avati <avati@xxxxxxxxxx>
---
Test case:
- concurrent read and write DDs with oflag=direct and iflag=direct set
in a few writes and a few reads
- artificially decrease 6th parameter to generic_file_direct_write to
simulate a partial write of the direct IO request and verify proper
buffered I/O for remaining offset and size with printk's and verify
write completion at backend
fs/fuse/dir.c | 3 -
fs/fuse/file.c | 124 ++++++++++++++++++++++++++++++++++++++++++++++++--------
2 files changed, 107 insertions(+), 20 deletions(-)
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 2066328..7e5dbd0 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -387,9 +387,6 @@ static int fuse_create_open(struct inode *dir, struct dentry *entry,
if (fc->no_create)
return -ENOSYS;
- if (flags & O_DIRECT)
- return -EINVAL;
-
forget = fuse_alloc_forget();
if (!forget)
return -ENOMEM;
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 4a199fd..9dd611b 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -194,10 +194,6 @@ 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;
@@ -932,17 +928,23 @@ static ssize_t fuse_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
struct file *file = iocb->ki_filp;
struct address_space *mapping = file->f_mapping;
size_t count = 0;
+ size_t ocount = 0;
ssize_t written = 0;
+ ssize_t written_buffered = 0;
struct inode *inode = mapping->host;
ssize_t err;
struct iov_iter i;
+ loff_t endbyte = 0;
WARN_ON(iocb->ki_pos != pos);
- err = generic_segment_checks(iov, &nr_segs, &count, VERIFY_READ);
+ ocount = 0;
+ err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ);
if (err)
return err;
+ count = ocount;
+
mutex_lock(&inode->i_mutex);
vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
@@ -962,11 +964,36 @@ static ssize_t fuse_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
file_update_time(file);
- iov_iter_init(&i, iov, nr_segs, count, 0);
- written = fuse_perform_write(file, mapping, &i, pos);
- if (written >= 0)
- iocb->ki_pos = pos + written;
+ if (file->f_flags & O_DIRECT) {
+ written = generic_file_direct_write(iocb, iov, &nr_segs,
+ pos, &iocb->ki_pos,
+ count, ocount);
+ if (written < 0 || written == count)
+ goto out;
+
+ pos += written;
+ count -= written;
+
+ iov_iter_init(&i, iov, nr_segs, count, written);
+ written_buffered = fuse_perform_write(file, mapping, &i, pos);
+ if (written_buffered < 0) {
+ err = written_buffered;
+ goto out;
+ }
+ endbyte = pos + written_buffered - 1;
+ err = filemap_write_and_wait_range(file->f_mapping, pos,
+ endbyte);
+ if (err)
+ goto out;
+ written += written_buffered;
+ iocb->ki_pos = pos + written_buffered;
+ } else {
+ iov_iter_init(&i, iov, nr_segs, count, 0);
+ written = fuse_perform_write(file, mapping, &i, pos);
+ if (written >= 0)
+ iocb->ki_pos = pos + written;
+ }
out:
current->backing_dev_info = NULL;
mutex_unlock(&inode->i_mutex);
@@ -1101,30 +1128,41 @@ static ssize_t fuse_direct_read(struct file *file, char __user *buf,
return res;
}
-static ssize_t fuse_direct_write(struct file *file, const char __user *buf,
- size_t count, loff_t *ppos)
+static ssize_t __fuse_direct_write(struct file *file, const char __user *buf,
+ size_t count, loff_t *ppos)
{
struct inode *inode = file->f_path.dentry->d_inode;
ssize_t res;
- if (is_bad_inode(inode))
- return -EIO;
-
- /* Don't allow parallel writes to the same file */
- mutex_lock(&inode->i_mutex);
res = generic_write_checks(file, ppos, &count, 0);
if (!res) {
res = fuse_direct_io(file, buf, count, ppos, 1);
if (res > 0)
fuse_write_update_size(inode, *ppos);
}
- mutex_unlock(&inode->i_mutex);
fuse_invalidate_attr(inode);
return res;
}
+static ssize_t fuse_direct_write(struct file *file, const char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ struct inode *inode = file->f_path.dentry->d_inode;
+ ssize_t res;
+
+ if (is_bad_inode(inode))
+ return -EIO;
+
+ /* Don't allow parallel writes to the same file */
+ mutex_lock(&inode->i_mutex);
+ res = __fuse_direct_write(file, buf, count, ppos);
+ mutex_unlock(&inode->i_mutex);
+
+ return res;
+}
+
static void fuse_writepage_free(struct fuse_conn *fc, struct fuse_req *req)
{
__free_page(req->pages[0]);
@@ -2077,6 +2115,57 @@ int fuse_notify_poll_wakeup(struct fuse_conn *fc,
return 0;
}
+static ssize_t fuse_loop_dio(struct file *filp, const struct iovec *iov,
+ unsigned long nr_segs, loff_t *ppos, int rw)
+{
+ const struct iovec *vector = iov;
+ ssize_t ret = 0;
+
+ while (nr_segs > 0) {
+ void __user *base;
+ size_t len;
+ ssize_t nr;
+
+ base = vector->iov_base;
+ len = vector->iov_len;
+ vector++;
+ nr_segs--;
+
+ if (rw == WRITE)
+ nr = __fuse_direct_write(filp, base, len, ppos);
+ else
+ nr = fuse_direct_read(filp, base, len, ppos);
+
+ if (nr < 0) {
+ if (!ret)
+ ret = nr;
+ break;
+ }
+ ret += nr;
+ if (nr != len)
+ break;
+ }
+
+ return ret;
+}
+
+
+static ssize_t
+fuse_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
+ loff_t offset, unsigned long nr_segs)
+{
+ ssize_t ret = 0;
+ struct file *file = NULL;
+ loff_t pos = 0;
+
+ file = iocb->ki_filp;
+ pos = offset;
+
+ ret = fuse_loop_dio(file, iov, nr_segs, &pos, rw);
+
+ return ret;
+}
+
static const struct file_operations fuse_file_operations = {
.llseek = fuse_file_llseek,
.read = do_sync_read,
@@ -2120,6 +2209,7 @@ static const struct address_space_operations fuse_file_aops = {
.readpages = fuse_readpages,
.set_page_dirty = __set_page_dirty_nobuffers,
.bmap = fuse_bmap,
+ .direct_IO = fuse_direct_IO,
};
void fuse_init_file_inode(struct inode *inode)
--
1.7.4.4
--
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