1 // SPDX-License-Identifier: GPL-2.0
5 * Copyright (c) 2024 CTERA Networks.
10 #include <linux/kernel.h>
11 #include <linux/sched.h>
12 #include <linux/file.h>
16 * Return true if need to wait for new opens in caching mode.
18 static inline bool fuse_is_io_cache_wait(struct fuse_inode *fi)
20 return READ_ONCE(fi->iocachectr) < 0;
24 * Start cached io mode.
26 * Blocks new parallel dio writes and waits for the in-progress parallel dio
29 int fuse_file_cached_io_start(struct inode *inode, struct fuse_file *ff)
31 struct fuse_inode *fi = get_fuse_inode(inode);
33 /* There are no io modes if server does not implement open */
34 if (!ff->release_args)
39 * Setting the bit advises new direct-io writes to use an exclusive
40 * lock - without it the wait below might be forever.
42 while (fuse_is_io_cache_wait(fi)) {
43 set_bit(FUSE_I_CACHE_IO_MODE, &fi->state);
44 spin_unlock(&fi->lock);
45 wait_event(fi->direct_io_waitq, !fuse_is_io_cache_wait(fi));
48 WARN_ON(ff->iomode == IOM_UNCACHED);
49 if (ff->iomode == IOM_NONE) {
50 ff->iomode = IOM_CACHED;
51 if (fi->iocachectr == 0)
52 set_bit(FUSE_I_CACHE_IO_MODE, &fi->state);
55 spin_unlock(&fi->lock);
59 static void fuse_file_cached_io_end(struct inode *inode, struct fuse_file *ff)
61 struct fuse_inode *fi = get_fuse_inode(inode);
64 WARN_ON(fi->iocachectr <= 0);
65 WARN_ON(ff->iomode != IOM_CACHED);
66 ff->iomode = IOM_NONE;
68 if (fi->iocachectr == 0)
69 clear_bit(FUSE_I_CACHE_IO_MODE, &fi->state);
70 spin_unlock(&fi->lock);
73 /* Start strictly uncached io mode where cache access is not allowed */
74 int fuse_file_uncached_io_start(struct inode *inode, struct fuse_file *ff)
76 struct fuse_inode *fi = get_fuse_inode(inode);
80 if (fi->iocachectr > 0) {
84 WARN_ON(ff->iomode != IOM_NONE);
86 ff->iomode = IOM_UNCACHED;
88 spin_unlock(&fi->lock);
92 void fuse_file_uncached_io_end(struct inode *inode, struct fuse_file *ff)
94 struct fuse_inode *fi = get_fuse_inode(inode);
97 WARN_ON(fi->iocachectr >= 0);
98 WARN_ON(ff->iomode != IOM_UNCACHED);
99 ff->iomode = IOM_NONE;
102 wake_up(&fi->direct_io_waitq);
103 spin_unlock(&fi->lock);
106 /* Request access to submit new io to inode via open file */
107 int fuse_file_io_open(struct file *file, struct inode *inode)
109 struct fuse_file *ff = file->private_data;
113 * io modes are not relevant with DAX and with server that does not
116 if (FUSE_IS_DAX(inode) || !ff->release_args)
120 * FOPEN_PARALLEL_DIRECT_WRITES requires FOPEN_DIRECT_IO.
122 if (!(ff->open_flags & FOPEN_DIRECT_IO))
123 ff->open_flags &= ~FOPEN_PARALLEL_DIRECT_WRITES;
126 * First caching file open enters caching inode io mode.
128 * Note that if user opens a file open with O_DIRECT, but server did
129 * not specify FOPEN_DIRECT_IO, a later fcntl() could remove O_DIRECT,
130 * so we put the inode in caching mode to prevent parallel dio.
132 if (ff->open_flags & FOPEN_DIRECT_IO)
135 err = fuse_file_cached_io_start(inode, ff);
142 pr_debug("failed to open file in requested io mode (open_flags=0x%x, err=%i).\n",
143 ff->open_flags, err);
145 * The file open mode determines the inode io mode.
146 * Using incorrect open mode is a server mistake, which results in
147 * user visible failure of open() with EIO error.
152 /* No more pending io and no new io possible to inode via open/mmapped file */
153 void fuse_file_io_release(struct fuse_file *ff, struct inode *inode)
156 * Last parallel dio close allows caching inode io mode.
157 * Last caching file close exits caching inode io mode.
159 switch (ff->iomode) {
164 fuse_file_uncached_io_end(inode, ff);
167 fuse_file_cached_io_end(inode, ff);