badf16621c
In order for the RCU to work, the file table array, sets and their sizes must be updated atomically. Instead of ensuring this through too many memory barriers, we put the arrays and their sizes in a separate structure. This patch takes the first step of putting the file table elements in a separate structure fdtable that is embedded withing files_struct. It also changes all the users to refer to the file table using files_fdtable() macro. Subsequent applciation of RCU becomes easier after this. Signed-off-by: Dipankar Sarma <dipankar@in.ibm.com> Signed-Off-By: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
92 lines
2.4 KiB
C
92 lines
2.4 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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/*
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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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struct fdtable {
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unsigned int max_fds;
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int max_fdset;
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int next_fd;
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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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};
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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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atomic_t count;
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spinlock_t file_lock; /* Protects all the below members. Nests inside tsk->alloc_lock */
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struct fdtable fdtab;
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fd_set close_on_exec_init;
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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) (&(files)->fdtab)
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extern void FASTCALL(__fput(struct file *));
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extern void FASTCALL(fput(struct file *));
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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 * FASTCALL(fget(unsigned int fd));
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extern struct file * FASTCALL(fget_light(unsigned int fd, int *fput_needed));
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extern void FASTCALL(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 void FASTCALL(put_unused_fd(unsigned int fd));
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struct kmem_cache_s;
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extern void filp_ctor(void * objp, struct kmem_cache_s *cachep, unsigned long cflags);
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extern void filp_dtor(void * objp, struct kmem_cache_s *cachep, unsigned long dflags);
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extern struct file ** alloc_fd_array(int);
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extern void free_fd_array(struct file **, int);
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extern fd_set *alloc_fdset(int);
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extern void free_fdset(fd_set *, int);
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extern int expand_files(struct files_struct *, int nr);
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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 = 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 FASTCALL(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 FASTCALL(put_files_struct(struct files_struct *fs));
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#endif /* __LINUX_FILE_H */
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