9cd6845511
While asynchronous reads mean a performance improvement in most cases, if the filesystem assumed that reads are synchronous, then async reads may degrade performance (filesystem may receive reads out of order, which can confuse it's own readahead logic). With sshfs a 1.5 to 4 times slowdown can be measured. There's also a need for userspace filesystems to know whether asynchronous reads are supported by the kernel or not. To achive these, negotiate in the INIT request whether async reads will be used and the maximum readahead value. Update interface version to 7.6 If userspace uses a version earlier than 7.6, then disable async reads, and set maximum readahead value to the maximum read size, as done in previous versions. Signed-off-by: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
504 lines
11 KiB
C
504 lines
11 KiB
C
/*
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FUSE: Filesystem in Userspace
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Copyright (C) 2001-2005 Miklos Szeredi <miklos@szeredi.hu>
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This program can be distributed under the terms of the GNU GPL.
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See the file COPYING.
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*/
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#include <linux/fuse.h>
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#include <linux/fs.h>
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#include <linux/wait.h>
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#include <linux/list.h>
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#include <linux/spinlock.h>
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#include <linux/mm.h>
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#include <linux/backing-dev.h>
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#include <asm/semaphore.h>
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/** Max number of pages that can be used in a single read request */
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#define FUSE_MAX_PAGES_PER_REQ 32
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/** If more requests are outstanding, then the operation will block */
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#define FUSE_MAX_OUTSTANDING 10
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/** It could be as large as PATH_MAX, but would that have any uses? */
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#define FUSE_NAME_MAX 1024
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/** If the FUSE_DEFAULT_PERMISSIONS flag is given, the filesystem
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module will check permissions based on the file mode. Otherwise no
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permission checking is done in the kernel */
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#define FUSE_DEFAULT_PERMISSIONS (1 << 0)
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/** If the FUSE_ALLOW_OTHER flag is given, then not only the user
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doing the mount will be allowed to access the filesystem */
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#define FUSE_ALLOW_OTHER (1 << 1)
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/** FUSE inode */
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struct fuse_inode {
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/** Inode data */
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struct inode inode;
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/** Unique ID, which identifies the inode between userspace
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* and kernel */
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u64 nodeid;
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/** Number of lookups on this inode */
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u64 nlookup;
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/** The request used for sending the FORGET message */
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struct fuse_req *forget_req;
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/** Time in jiffies until the file attributes are valid */
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unsigned long i_time;
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};
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/** FUSE specific file data */
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struct fuse_file {
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/** Request reserved for flush and release */
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struct fuse_req *release_req;
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/** File handle used by userspace */
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u64 fh;
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};
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/** One input argument of a request */
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struct fuse_in_arg {
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unsigned size;
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const void *value;
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};
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/** The request input */
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struct fuse_in {
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/** The request header */
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struct fuse_in_header h;
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/** True if the data for the last argument is in req->pages */
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unsigned argpages:1;
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/** Number of arguments */
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unsigned numargs;
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/** Array of arguments */
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struct fuse_in_arg args[3];
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};
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/** One output argument of a request */
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struct fuse_arg {
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unsigned size;
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void *value;
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};
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/** The request output */
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struct fuse_out {
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/** Header returned from userspace */
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struct fuse_out_header h;
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/*
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* The following bitfields are not changed during the request
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* processing
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*/
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/** Last argument is variable length (can be shorter than
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arg->size) */
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unsigned argvar:1;
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/** Last argument is a list of pages to copy data to */
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unsigned argpages:1;
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/** Zero partially or not copied pages */
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unsigned page_zeroing:1;
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/** Number or arguments */
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unsigned numargs;
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/** Array of arguments */
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struct fuse_arg args[3];
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};
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/** The request state */
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enum fuse_req_state {
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FUSE_REQ_INIT = 0,
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FUSE_REQ_PENDING,
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FUSE_REQ_READING,
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FUSE_REQ_SENT,
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FUSE_REQ_FINISHED
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};
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struct fuse_conn;
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/**
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* A request to the client
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*/
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struct fuse_req {
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/** This can be on either unused_list, pending processing or
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io lists in fuse_conn */
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struct list_head list;
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/** Entry on the background list */
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struct list_head bg_entry;
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/** refcount */
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atomic_t count;
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/*
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* The following bitfields are either set once before the
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* request is queued or setting/clearing them is protected by
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* fuse_lock
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*/
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/** True if the request has reply */
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unsigned isreply:1;
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/** The request is preallocated */
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unsigned preallocated:1;
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/** The request was interrupted */
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unsigned interrupted:1;
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/** Request is sent in the background */
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unsigned background:1;
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/** Data is being copied to/from the request */
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unsigned locked:1;
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/** State of the request */
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enum fuse_req_state state;
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/** The request input */
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struct fuse_in in;
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/** The request output */
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struct fuse_out out;
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/** Used to wake up the task waiting for completion of request*/
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wait_queue_head_t waitq;
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/** Data for asynchronous requests */
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union {
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struct fuse_forget_in forget_in;
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struct fuse_release_in release_in;
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struct fuse_init_in init_in;
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struct fuse_init_out init_out;
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struct fuse_read_in read_in;
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} misc;
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/** page vector */
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struct page *pages[FUSE_MAX_PAGES_PER_REQ];
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/** number of pages in vector */
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unsigned num_pages;
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/** offset of data on first page */
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unsigned page_offset;
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/** Inode used in the request */
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struct inode *inode;
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/** Second inode used in the request (or NULL) */
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struct inode *inode2;
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/** File used in the request (or NULL) */
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struct file *file;
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/** Request completion callback */
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void (*end)(struct fuse_conn *, struct fuse_req *);
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};
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/**
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* A Fuse connection.
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*
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* This structure is created, when the filesystem is mounted, and is
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* destroyed, when the client device is closed and the filesystem is
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* unmounted.
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*/
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struct fuse_conn {
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/** The user id for this mount */
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uid_t user_id;
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/** The group id for this mount */
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gid_t group_id;
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/** The fuse mount flags for this mount */
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unsigned flags;
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/** Maximum read size */
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unsigned max_read;
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/** Maximum write size */
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unsigned max_write;
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/** Readers of the connection are waiting on this */
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wait_queue_head_t waitq;
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/** The list of pending requests */
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struct list_head pending;
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/** The list of requests being processed */
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struct list_head processing;
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/** The list of requests under I/O */
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struct list_head io;
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/** Requests put in the background (RELEASE or any other
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interrupted request) */
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struct list_head background;
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/** Controls the maximum number of outstanding requests */
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struct semaphore outstanding_sem;
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/** This counts the number of outstanding requests if
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outstanding_sem would go negative */
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unsigned outstanding_debt;
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/** RW semaphore for exclusion with fuse_put_super() */
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struct rw_semaphore sbput_sem;
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/** The list of unused requests */
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struct list_head unused_list;
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/** The next unique request id */
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u64 reqctr;
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/** Mount is active */
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unsigned mounted;
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/** Connection established, cleared on umount, connection
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abort and device release */
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unsigned connected;
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/** Connection failed (version mismatch). Cannot race with
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setting other bitfields since it is only set once in INIT
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reply, before any other request, and never cleared */
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unsigned conn_error : 1;
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/** Do readpages asynchronously? Only set in INIT */
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unsigned async_read : 1;
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/*
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* The following bitfields are only for optimization purposes
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* and hence races in setting them will not cause malfunction
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*/
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/** Is fsync not implemented by fs? */
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unsigned no_fsync : 1;
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/** Is fsyncdir not implemented by fs? */
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unsigned no_fsyncdir : 1;
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/** Is flush not implemented by fs? */
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unsigned no_flush : 1;
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/** Is setxattr not implemented by fs? */
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unsigned no_setxattr : 1;
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/** Is getxattr not implemented by fs? */
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unsigned no_getxattr : 1;
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/** Is listxattr not implemented by fs? */
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unsigned no_listxattr : 1;
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/** Is removexattr not implemented by fs? */
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unsigned no_removexattr : 1;
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/** Is access not implemented by fs? */
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unsigned no_access : 1;
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/** Is create not implemented by fs? */
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unsigned no_create : 1;
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/** The number of requests waiting for completion */
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atomic_t num_waiting;
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/** Negotiated minor version */
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unsigned minor;
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/** Backing dev info */
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struct backing_dev_info bdi;
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/** kobject */
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struct kobject kobj;
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};
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static inline struct fuse_conn *get_fuse_conn_super(struct super_block *sb)
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{
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return sb->s_fs_info;
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}
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static inline struct fuse_conn *get_fuse_conn(struct inode *inode)
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{
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return get_fuse_conn_super(inode->i_sb);
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}
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static inline struct fuse_conn *get_fuse_conn_kobj(struct kobject *obj)
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{
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return container_of(obj, struct fuse_conn, kobj);
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}
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static inline struct fuse_inode *get_fuse_inode(struct inode *inode)
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{
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return container_of(inode, struct fuse_inode, inode);
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}
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static inline u64 get_node_id(struct inode *inode)
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{
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return get_fuse_inode(inode)->nodeid;
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}
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/** Device operations */
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extern struct file_operations fuse_dev_operations;
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/**
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* This is the single global spinlock which protects FUSE's structures
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*
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* The following data is protected by this lock:
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*
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* - the private_data field of the device file
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* - the s_fs_info field of the super block
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* - unused_list, pending, processing lists in fuse_conn
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* - background list in fuse_conn
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* - the unique request ID counter reqctr in fuse_conn
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* - the sb (super_block) field in fuse_conn
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* - the file (device file) field in fuse_conn
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*/
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extern spinlock_t fuse_lock;
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/**
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* Get a filled in inode
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*/
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struct inode *fuse_iget(struct super_block *sb, unsigned long nodeid,
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int generation, struct fuse_attr *attr);
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/**
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* Send FORGET command
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*/
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void fuse_send_forget(struct fuse_conn *fc, struct fuse_req *req,
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unsigned long nodeid, u64 nlookup);
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/**
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* Initialize READ or READDIR request
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*/
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void fuse_read_fill(struct fuse_req *req, struct file *file,
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struct inode *inode, loff_t pos, size_t count, int opcode);
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/**
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* Send OPEN or OPENDIR request
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*/
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int fuse_open_common(struct inode *inode, struct file *file, int isdir);
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struct fuse_file *fuse_file_alloc(void);
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void fuse_file_free(struct fuse_file *ff);
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void fuse_finish_open(struct inode *inode, struct file *file,
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struct fuse_file *ff, struct fuse_open_out *outarg);
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/**
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* Send a RELEASE request
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*/
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void fuse_send_release(struct fuse_conn *fc, struct fuse_file *ff,
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u64 nodeid, struct inode *inode, int flags, int isdir);
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/**
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* Send RELEASE or RELEASEDIR request
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*/
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int fuse_release_common(struct inode *inode, struct file *file, int isdir);
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/**
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* Send FSYNC or FSYNCDIR request
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*/
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int fuse_fsync_common(struct file *file, struct dentry *de, int datasync,
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int isdir);
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/**
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* Initialize file operations on a regular file
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*/
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void fuse_init_file_inode(struct inode *inode);
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/**
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* Initialize inode operations on regular files and special files
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*/
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void fuse_init_common(struct inode *inode);
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/**
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* Initialize inode and file operations on a directory
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*/
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void fuse_init_dir(struct inode *inode);
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/**
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* Initialize inode operations on a symlink
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*/
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void fuse_init_symlink(struct inode *inode);
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/**
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* Change attributes of an inode
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*/
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void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr);
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/**
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* Initialize the client device
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*/
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int fuse_dev_init(void);
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/**
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* Cleanup the client device
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*/
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void fuse_dev_cleanup(void);
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/**
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* Allocate a request
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*/
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struct fuse_req *fuse_request_alloc(void);
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/**
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* Free a request
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*/
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void fuse_request_free(struct fuse_req *req);
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/**
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* Reinitialize a request, the preallocated flag is left unmodified
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*/
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void fuse_reset_request(struct fuse_req *req);
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/**
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* Reserve a preallocated request
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*/
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struct fuse_req *fuse_get_request(struct fuse_conn *fc);
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/**
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* Decrement reference count of a request. If count goes to zero put
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* on unused list (preallocated) or free request (not preallocated).
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*/
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void fuse_put_request(struct fuse_conn *fc, struct fuse_req *req);
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/**
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* Send a request (synchronous)
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*/
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void request_send(struct fuse_conn *fc, struct fuse_req *req);
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/**
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* Send a request with no reply
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*/
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void request_send_noreply(struct fuse_conn *fc, struct fuse_req *req);
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/**
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* Send a request in the background
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*/
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void request_send_background(struct fuse_conn *fc, struct fuse_req *req);
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/**
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* Release inodes and file associated with background request
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*/
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void fuse_release_background(struct fuse_req *req);
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/* Abort all requests */
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void fuse_abort_conn(struct fuse_conn *fc);
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/**
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* Get the attributes of a file
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*/
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int fuse_do_getattr(struct inode *inode);
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/**
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* Invalidate inode attributes
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*/
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void fuse_invalidate_attr(struct inode *inode);
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