From 4273b793ec68753cc3fcf5be7cbfd88c2be2058d Mon Sep 17 00:00:00 2001 From: Anand Avati Date: Fri, 17 Feb 2012 12:46:25 -0500 Subject: 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 Reviewed-by: Jeff Moyer Signed-off-by: Miklos Szeredi --- fs/fuse/dir.c | 3 -- fs/fuse/file.c | 129 +++++++++++++++++++++++++++++++++++++++++++++++++-------- 2 files changed, 112 insertions(+), 20 deletions(-) (limited to 'fs/fuse') diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c index da379070fab..df5ac048dc7 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 4a199fd93fb..8ca007d09c9 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 +964,41 @@ 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; + + invalidate_mapping_pages(file->f_mapping, + pos >> PAGE_CACHE_SHIFT, + endbyte >> PAGE_CACHE_SHIFT); + + 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 +1133,41 @@ 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 +2120,57 @@ 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 +2214,7 @@ 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) -- cgit v1.2.3