493 lines
11 KiB
C
493 lines
11 KiB
C
/*
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FUSE: Filesystem in Userspace
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Copyright (C) 2001-2006 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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/** Maximum number of outstanding background requests */
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#define FUSE_MAX_BACKGROUND 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 pending processing or io lists in
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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_conn->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 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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/** Lock protecting accessess to members of this structure */
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spinlock_t lock;
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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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/** Number of requests currently in the background */
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unsigned num_background;
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/** Flag indicating if connection is blocked. This will be
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the case before the INIT reply is received, and if there
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are too many outstading backgrounds requests */
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int blocked;
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/** waitq for blocked connection */
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wait_queue_head_t blocked_waitq;
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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 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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/** O_ASYNC requests */
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struct fasync_struct *fasync;
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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 const struct file_operations fuse_dev_operations;
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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_req(struct fuse_conn *fc);
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/**
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* Decrement reference count of a request. If count goes to zero free
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* the request.
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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_conn *fc, 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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