fuse: O_DIRECT support for files
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@redhat.com> Reviewed-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
This commit is contained in:
Anand Avati
Miklos Szeredi
Родитель
ac45d61357
Коммит
4273b793ec
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@ -387,9 +387,6 @@ static int fuse_create_open(struct inode *dir, struct dentry *entry,
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if (fc->no_create)
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return -ENOSYS;
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if (flags & O_DIRECT)
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return -EINVAL;
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forget = fuse_alloc_forget();
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if (!forget)
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return -ENOMEM;
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129
fs/fuse/file.c
129
fs/fuse/file.c
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@ -194,10 +194,6 @@ int fuse_open_common(struct inode *inode, struct file *file, bool isdir)
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struct fuse_conn *fc = get_fuse_conn(inode);
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int err;
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/* VFS checks this, but only _after_ ->open() */
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if (file->f_flags & O_DIRECT)
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return -EINVAL;
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err = generic_file_open(inode, file);
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if (err)
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return err;
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@ -932,17 +928,23 @@ static ssize_t fuse_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
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struct file *file = iocb->ki_filp;
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struct address_space *mapping = file->f_mapping;
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size_t count = 0;
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size_t ocount = 0;
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ssize_t written = 0;
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ssize_t written_buffered = 0;
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struct inode *inode = mapping->host;
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ssize_t err;
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struct iov_iter i;
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loff_t endbyte = 0;
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WARN_ON(iocb->ki_pos != pos);
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err = generic_segment_checks(iov, &nr_segs, &count, VERIFY_READ);
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ocount = 0;
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err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ);
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if (err)
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return err;
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count = ocount;
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mutex_lock(&inode->i_mutex);
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vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
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@ -962,11 +964,41 @@ static ssize_t fuse_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
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file_update_time(file);
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iov_iter_init(&i, iov, nr_segs, count, 0);
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written = fuse_perform_write(file, mapping, &i, pos);
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if (written >= 0)
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iocb->ki_pos = pos + written;
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if (file->f_flags & O_DIRECT) {
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written = generic_file_direct_write(iocb, iov, &nr_segs,
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pos, &iocb->ki_pos,
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count, ocount);
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if (written < 0 || written == count)
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goto out;
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pos += written;
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count -= written;
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iov_iter_init(&i, iov, nr_segs, count, written);
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written_buffered = fuse_perform_write(file, mapping, &i, pos);
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if (written_buffered < 0) {
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err = written_buffered;
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goto out;
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}
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endbyte = pos + written_buffered - 1;
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err = filemap_write_and_wait_range(file->f_mapping, pos,
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endbyte);
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if (err)
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goto out;
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invalidate_mapping_pages(file->f_mapping,
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pos >> PAGE_CACHE_SHIFT,
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endbyte >> PAGE_CACHE_SHIFT);
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written += written_buffered;
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iocb->ki_pos = pos + written_buffered;
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} else {
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iov_iter_init(&i, iov, nr_segs, count, 0);
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written = fuse_perform_write(file, mapping, &i, pos);
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if (written >= 0)
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iocb->ki_pos = pos + written;
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}
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out:
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current->backing_dev_info = NULL;
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mutex_unlock(&inode->i_mutex);
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@ -1101,6 +1133,24 @@ static ssize_t fuse_direct_read(struct file *file, char __user *buf,
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return res;
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}
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static ssize_t __fuse_direct_write(struct file *file, const char __user *buf,
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size_t count, loff_t *ppos)
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{
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struct inode *inode = file->f_path.dentry->d_inode;
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ssize_t res;
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res = generic_write_checks(file, ppos, &count, 0);
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if (!res) {
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res = fuse_direct_io(file, buf, count, ppos, 1);
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if (res > 0)
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fuse_write_update_size(inode, *ppos);
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}
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fuse_invalidate_attr(inode);
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return res;
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}
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static ssize_t fuse_direct_write(struct file *file, const char __user *buf,
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size_t count, loff_t *ppos)
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{
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@ -1112,16 +1162,9 @@ static ssize_t fuse_direct_write(struct file *file, const char __user *buf,
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/* Don't allow parallel writes to the same file */
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mutex_lock(&inode->i_mutex);
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res = generic_write_checks(file, ppos, &count, 0);
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if (!res) {
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res = fuse_direct_io(file, buf, count, ppos, 1);
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if (res > 0)
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fuse_write_update_size(inode, *ppos);
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}
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res = __fuse_direct_write(file, buf, count, ppos);
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mutex_unlock(&inode->i_mutex);
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fuse_invalidate_attr(inode);
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return res;
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}
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@ -2077,6 +2120,57 @@ int fuse_notify_poll_wakeup(struct fuse_conn *fc,
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return 0;
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}
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static ssize_t fuse_loop_dio(struct file *filp, const struct iovec *iov,
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unsigned long nr_segs, loff_t *ppos, int rw)
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{
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const struct iovec *vector = iov;
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ssize_t ret = 0;
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while (nr_segs > 0) {
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void __user *base;
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size_t len;
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ssize_t nr;
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base = vector->iov_base;
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len = vector->iov_len;
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vector++;
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nr_segs--;
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if (rw == WRITE)
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nr = __fuse_direct_write(filp, base, len, ppos);
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else
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nr = fuse_direct_read(filp, base, len, ppos);
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if (nr < 0) {
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if (!ret)
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ret = nr;
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break;
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}
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ret += nr;
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if (nr != len)
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break;
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}
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return ret;
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}
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static ssize_t
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fuse_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
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loff_t offset, unsigned long nr_segs)
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{
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ssize_t ret = 0;
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struct file *file = NULL;
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loff_t pos = 0;
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file = iocb->ki_filp;
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pos = offset;
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ret = fuse_loop_dio(file, iov, nr_segs, &pos, rw);
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return ret;
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}
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static const struct file_operations fuse_file_operations = {
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.llseek = fuse_file_llseek,
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.read = do_sync_read,
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@ -2120,6 +2214,7 @@ static const struct address_space_operations fuse_file_aops = {
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.readpages = fuse_readpages,
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.set_page_dirty = __set_page_dirty_nobuffers,
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.bmap = fuse_bmap,
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.direct_IO = fuse_direct_IO,
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};
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void fuse_init_file_inode(struct inode *inode)
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