aceaf78da9
If someone decides to demote a file from r/w to just r/o, they can use this same code as __fput(). NFS does just that, and will use this in the next patch. AV: drop write access in __fput() only after we evict from file list. Signed-off-by: Dave Hansen <haveblue@us.ibm.com> Cc: Erez Zadok <ezk@cs.sunysb.edu> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Cc: "J Bruce Fields" <bfields@fieldses.org> Acked-by: Al Viro <viro@ZenIV.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
125 lines
3.1 KiB
C
125 lines
3.1 KiB
C
/*
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* Wrapper functions for accessing the file_struct fd array.
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*/
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#ifndef __LINUX_FILE_H
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#define __LINUX_FILE_H
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#include <asm/atomic.h>
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#include <linux/posix_types.h>
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#include <linux/compiler.h>
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#include <linux/spinlock.h>
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#include <linux/rcupdate.h>
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#include <linux/types.h>
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/*
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* The default fd array needs to be at least BITS_PER_LONG,
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* as this is the granularity returned by copy_fdset().
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*/
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#define NR_OPEN_DEFAULT BITS_PER_LONG
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/*
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* The embedded_fd_set is a small fd_set,
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* suitable for most tasks (which open <= BITS_PER_LONG files)
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*/
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struct embedded_fd_set {
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unsigned long fds_bits[1];
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};
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struct fdtable {
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unsigned int max_fds;
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struct file ** fd; /* current fd array */
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fd_set *close_on_exec;
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fd_set *open_fds;
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struct rcu_head rcu;
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struct fdtable *next;
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};
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/*
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* Open file table structure
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*/
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struct files_struct {
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/*
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* read mostly part
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*/
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atomic_t count;
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struct fdtable *fdt;
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struct fdtable fdtab;
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/*
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* written part on a separate cache line in SMP
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*/
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spinlock_t file_lock ____cacheline_aligned_in_smp;
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int next_fd;
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struct embedded_fd_set close_on_exec_init;
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struct embedded_fd_set open_fds_init;
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struct file * fd_array[NR_OPEN_DEFAULT];
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};
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#define files_fdtable(files) (rcu_dereference((files)->fdt))
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extern struct kmem_cache *filp_cachep;
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extern void __fput(struct file *);
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extern void fput(struct file *);
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extern void drop_file_write_access(struct file *file);
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struct file_operations;
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struct vfsmount;
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struct dentry;
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extern int init_file(struct file *, struct vfsmount *mnt,
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struct dentry *dentry, mode_t mode,
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const struct file_operations *fop);
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extern struct file *alloc_file(struct vfsmount *, struct dentry *dentry,
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mode_t mode, const struct file_operations *fop);
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static inline void fput_light(struct file *file, int fput_needed)
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{
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if (unlikely(fput_needed))
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fput(file);
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}
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extern struct file *fget(unsigned int fd);
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extern struct file *fget_light(unsigned int fd, int *fput_needed);
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extern void set_close_on_exec(unsigned int fd, int flag);
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extern void put_filp(struct file *);
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extern int get_unused_fd(void);
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extern int get_unused_fd_flags(int flags);
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extern void put_unused_fd(unsigned int fd);
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struct kmem_cache;
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extern int expand_files(struct files_struct *, int nr);
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extern void free_fdtable_rcu(struct rcu_head *rcu);
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extern void __init files_defer_init(void);
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static inline void free_fdtable(struct fdtable *fdt)
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{
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call_rcu(&fdt->rcu, free_fdtable_rcu);
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}
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static inline struct file * fcheck_files(struct files_struct *files, unsigned int fd)
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{
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struct file * file = NULL;
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struct fdtable *fdt = files_fdtable(files);
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if (fd < fdt->max_fds)
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file = rcu_dereference(fdt->fd[fd]);
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return file;
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}
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/*
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* Check whether the specified fd has an open file.
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*/
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#define fcheck(fd) fcheck_files(current->files, fd)
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extern void fd_install(unsigned int fd, struct file *file);
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struct task_struct;
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struct files_struct *get_files_struct(struct task_struct *);
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void put_files_struct(struct files_struct *fs);
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void reset_files_struct(struct task_struct *, struct files_struct *);
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extern struct kmem_cache *files_cachep;
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#endif /* __LINUX_FILE_H */
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