fs.h

Axis 221 camera embedded programing interface

/** 
 * enum positive_aop_returns - aop return codes with specific semantics
 *
 * @AOP_WRITEPAGE_ACTIVATE: Informs the caller that page writeback has
 * 			    completed, that the page is still locked, and
 * 			    should be considered active.  The VM uses this hint
 * 			    to return the page to the active list -- it won't
 * 			    be a candidate for writeback again in the near
 * 			    future.  Other callers must be careful to unlock
 * 			    the page if they get this return.  Returned by
 * 			    writepage(); 
 *
 * @AOP_TRUNCATED_PAGE: The AOP method that was handed a locked page has
 *  			unlocked it and the page might have been truncated.
 *  			The caller should back up to acquiring a new page and
 *  			trying again.  The aop will be taking reasonable
 *  			precautions not to livelock.  If the caller held a page
 *  			reference, it should drop it before retrying.  Returned
 *  			by readpage(), prepare_write(), and commit_write().
 *
 * address_space_operation functions return these large constants to indicate
 * special semantics to the caller.  These are much larger than the bytes in a
 * page to allow for functions that return the number of bytes operated on in a
 * given page.
 */

enum positive_aop_returns {
	AOP_WRITEPAGE_ACTIVATE	= 0x80000,
	AOP_TRUNCATED_PAGE	= 0x80001,
};

/*
 * oh the beauties of C type declarations.
 */
struct page;
struct address_space;
struct writeback_control;

struct address_space_operations {
	int (*writepage)(struct page *page, struct writeback_control *wbc);
	int (*readpage)(struct file *, struct page *);
	void (*sync_page)(struct page *);

	/* Write back some dirty pages from this mapping. */
	int (*writepages)(struct address_space *, struct writeback_control *);

	/* Set a page dirty.  Return true if this dirtied it */
	int (*set_page_dirty)(struct page *page);

	int (*readpages)(struct file *filp, struct address_space *mapping,
			struct list_head *pages, unsigned nr_pages);

	/*
	 * ext3 requires that a successful prepare_write() call be followed
	 * by a commit_write() call - they must be balanced
	 */
	int (*prepare_write)(struct file *, struct page *, unsigned, unsigned);
	int (*commit_write)(struct file *, struct page *, unsigned, unsigned);
	/* Unfortunately this kludge is needed for FIBMAP. Don't use it */
	sector_t (*bmap)(struct address_space *, sector_t);
	void (*invalidatepage) (struct page *, unsigned long);
	int (*releasepage) (struct page *, gfp_t);
	ssize_t (*direct_IO)(int, struct kiocb *, const struct iovec *iov,
			loff_t offset, unsigned long nr_segs);
	struct page* (*get_xip_page)(struct address_space *, sector_t,
			int);
	/* migrate the contents of a page to the specified target */
	int (*migratepage) (struct address_space *,
			struct page *, struct page *);
	int (*launder_page) (struct page *);
};

struct backing_dev_info;
struct address_space {
	struct inode		*host;		/* owner: inode, block_device */
	struct radix_tree_root	page_tree;	/* radix tree of all pages */
	rwlock_t		tree_lock;	/* and rwlock protecting it */
	unsigned int		i_mmap_writable;/* count VM_SHARED mappings */
	struct prio_tree_root	i_mmap;		/* tree of private and shared mappings */
	struct list_head	i_mmap_nonlinear;/*list VM_NONLINEAR mappings */
	spinlock_t		i_mmap_lock;	/* protect tree, count, list */
	unsigned int		truncate_count;	/* Cover race condition with truncate */
	unsigned long		nrpages;	/* number of total pages */
	pgoff_t			writeback_index;/* writeback starts here */
	const struct address_space_operations *a_ops;	/* methods */
	unsigned long		flags;		/* error bits/gfp mask */
	struct backing_dev_info *backing_dev_info; /* device readahead, etc */
	spinlock_t		private_lock;	/* for use by the address_space */
	struct list_head	private_list;	/* ditto */
	struct address_space	*assoc_mapping;	/* ditto */
} __attribute__((aligned(sizeof(long))));
	/*
	 * On most architectures that alignment is already the case; but
	 * must be enforced here for CRIS, to let the least signficant bit
	 * of struct page's "mapping" pointer be used for PAGE_MAPPING_ANON.
	 */

struct block_device {
	dev_t			bd_dev;  /* not a kdev_t - it's a search key */
	struct inode *		bd_inode;	/* will die */
	int			bd_openers;
	struct mutex		bd_mutex;	/* open/close mutex */
	struct semaphore	bd_mount_sem;
	struct list_head	bd_inodes;
	void *			bd_holder;
	int			bd_holders;
#ifdef CONFIG_SYSFS
	struct list_head	bd_holder_list;
#endif
	struct block_device *	bd_contains;
	unsigned		bd_block_size;
	struct hd_struct *	bd_part;
	/* number of times partitions within this device have been opened. */
	unsigned		bd_part_count;
	int			bd_invalidated;
	struct gendisk *	bd_disk;
	struct list_head	bd_list;
	struct backing_dev_info *bd_inode_backing_dev_info;
	/*
	 * Private data.  You must have bd_claim'ed the block_device
	 * to use this.  NOTE:  bd_claim allows an owner to claim
	 * the same device multiple times, the owner must take special
	 * care to not mess up bd_private for that case.
	 */
	unsigned long		bd_private;
};

/*
 * Radix-tree tags, for tagging dirty and writeback pages within the pagecache
 * radix trees
 */
#define PAGECACHE_TAG_DIRTY	0
#define PAGECACHE_TAG_WRITEBACK	1

int mapping_tagged(struct address_space *mapping, int tag);

/*
 * Might pages of this file be mapped into userspace?
 */
static inline int mapping_mapped(struct address_space *mapping)
{
	return	!prio_tree_empty(&mapping->i_mmap) ||
		!list_empty(&mapping->i_mmap_nonlinear);
}

/*
 * Might pages of this file have been modified in userspace?
 * Note that i_mmap_writable counts all VM_SHARED vmas: do_mmap_pgoff
 * marks vma as VM_SHARED if it is shared, and the file was opened for
 * writing i.e. vma may be mprotected writable even if now readonly.
 */
static inline int mapping_writably_mapped(struct address_space *mapping)
{
	return mapping->i_mmap_writable != 0;
}

/*
 * Use sequence counter to get consistent i_size on 32-bit processors.
 */
#if BITS_PER_LONG==32 && defined(CONFIG_SMP)
#include <linux/seqlock.h>
#define __NEED_I_SIZE_ORDERED
#define i_size_ordered_init(inode) seqcount_init(&inode->i_size_seqcount)
#else
#define i_size_ordered_init(inode) do { } while (0)
#endif

struct inode {
	struct hlist_node	i_hash;
	struct list_head	i_list;
	struct list_head	i_sb_list;
	struct list_head	i_dentry;
	unsigned long		i_ino;
	atomic_t		i_count;
	unsigned int		i_nlink;
	uid_t			i_uid;
	gid_t			i_gid;
	dev_t			i_rdev;
	unsigned long		i_version;
	loff_t			i_size;
#ifdef __NEED_I_SIZE_ORDERED
	seqcount_t		i_size_seqcount;
#endif
	struct timespec		i_atime;
	struct timespec		i_mtime;
	struct timespec		i_ctime;
	unsigned int		i_blkbits;
	blkcnt_t		i_blocks;
	unsigned short          i_bytes;
	umode_t			i_mode;
	spinlock_t		i_lock;	/* i_blocks, i_bytes, maybe i_size */
	struct mutex		i_mutex;
	struct rw_semaphore	i_alloc_sem;
	struct inode_operations	*i_op;
	const struct file_operations	*i_fop;	/* former ->i_op->default_file_ops */
	struct super_block	*i_sb;
	struct file_lock	*i_flock;
	struct address_space	*i_mapping;
	/* The LSB in i_data below is used for the PAGE_MAPPING_ANON flag. 
	 * This assumes that the address of this member isn't odd which
	 * is not true for all architectures. Force the compiler to align it.
	 */
	struct address_space	i_data __attribute__ ((aligned(4)));
#ifdef CONFIG_QUOTA
	struct dquot		*i_dquot[MAXQUOTAS];
#endif
	struct list_head	i_devices;
	union {
		struct pipe_inode_info	*i_pipe;
		struct block_device	*i_bdev;
		struct cdev		*i_cdev;
	};
	int			i_cindex;

	__u32			i_generation;

#ifdef CONFIG_DNOTIFY
	unsigned long		i_dnotify_mask; /* Directory notify events */
	struct dnotify_struct	*i_dnotify; /* for directory notifications */
#endif

#ifdef CONFIG_INOTIFY
	struct list_head	inotify_watches; /* watches on this inode */
	struct mutex		inotify_mutex;	/* protects the watches list */
#endif

	unsigned long		i_state;
	unsigned long		dirtied_when;	/* jiffies of first dirtying */

	unsigned int		i_flags;

	atomic_t		i_writecount;
#ifdef CONFIG_SECURITY
	void			*i_security;
#endif
	void			*i_private; /* fs or device private pointer */
};

/*
 * inode->i_mutex nesting subclasses for the lock validator:
 *
 * 0: the object of the current VFS operation
 * 1: parent
 * 2: child/target
 * 3: quota file
 *
 * The locking order between these classes is
 * parent -> child -> normal -> xattr -> quota
 */
enum inode_i_mutex_lock_class
{
	I_MUTEX_NORMAL,
	I_MUTEX_PARENT,
	I_MUTEX_CHILD,
	I_MUTEX_XATTR,
	I_MUTEX_QUOTA
};

extern void inode_double_lock(struct inode *inode1, struct inode *inode2);
extern void inode_double_unlock(struct inode *inode1, struct inode *inode2);

/*
 * NOTE: in a 32bit arch with a preemptable kernel and
 * an UP compile the i_size_read/write must be atomic
 * with respect to the local cpu (unlike with preempt disabled),
 * but they don't need to be atomic with respect to other cpus like in
 * true SMP (so they need either to either locally disable irq around
 * the read or for example on x86 they can be still implemented as a
 * cmpxchg8b without the need of the lock prefix). For SMP compiles
 * and 64bit archs it makes no difference if preempt is enabled or not.
 */
static inline loff_t i_size_read(const struct inode *inode)
{
#if BITS_PER_LONG==32 && defined(CONFIG_SMP)
	loff_t i_size;
	unsigned int seq;

	do {
		seq = read_seqcount_begin(&inode->i_size_seqcount);
		i_size = inode->i_size;
	} while (read_seqcount_retry(&inode->i_size_seqcount, seq));
	return i_size;
#elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPT)
	loff_t i_size;

	preempt_disable();
	i_size = inode->i_size;
	preempt_enable();
	return i_size;
#else
	return inode->i_size;
#endif
}

/*
 * NOTE: unlike i_size_read(), i_size_write() does need locking around it
 * (normally i_mutex), otherwise on 32bit/SMP an update of i_size_seqcount
 * can be lost, resulting in subsequent i_size_read() calls spinning forever.
 */
static inline void i_size_write(struct inode *inode, loff_t i_size)
{
#if BITS_PER_LONG==32 && defined(CONFIG_SMP)
	write_seqcount_begin(&inode->i_size_seqcount);
	inode->i_size = i_size;
	write_seqcount_end(&inode->i_size_seqcount);
#elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPT)
	preempt_disable();
	inode->i_size = i_size;
	preempt_enable();
#else
	inode->i_size = i_size;
#endif
}

static inline unsigned iminor(const struct inode *inode)
{
	return MINOR(inode->i_rdev);
}

static inline unsigned imajor(const struct inode *inode)
{
	return MAJOR(inode->i_rdev);
}

extern struct block_device *I_BDEV(struct inode *inode);

struct fown_struct {
	rwlock_t lock;          /* protects pid, uid, euid fields */
	struct pid *pid;	/* pid or -pgrp where SIGIO should be sent */
	enum pid_type pid_type;	/* Kind of process group SIGIO should be sent to */
	uid_t uid, euid;	/* uid/euid of process setting the owner */
	int signum;		/* posix.1b rt signal to be delivered on IO */
};

/*
 * Track a single file's readahead state
 */
struct file_ra_state {
	unsigned long start;		/* Current window */
	unsigned long size;
	unsigned long flags;		/* ra flags RA_FLAG_xxx*/
	unsigned long cache_hit;	/* cache hit count*/
	unsigned long prev_page;	/* Cache last read() position */
	unsigned long ahead_start;	/* Ahead window */
	unsigned long ahead_size;
	unsigned long ra_pages;		/* Maximum readahead window */
	unsigned long mmap_hit;		/* Cache hit stat for mmap accesses */
	unsigned long mmap_miss;	/* Cache miss stat for mmap accesses */
};
#define RA_FLAG_MISS 0x01	/* a cache miss occured against this file */
#define RA_FLAG_INCACHE 0x02	/* file is already in cache */

struct file {
	/*
	 * fu_list becomes invalid after file_free is called and queued via
	 * fu_rcuhead for RCU freeing
	 */