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[PATCH] merge locate_fd() and get_unused_fd()

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New primitive: alloc_fd(start, flags).  get_unused_fd() and
get_unused_fd_flags() become wrappers on top of it.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro
2008-07-30 04:13:04 -04:00
parent a1bc6eb4b4
commit 1027abe882
4 changed files with 76 additions and 129 deletions
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61
fs/file.c
View File

@ -6,6 +6,7 @@
* Manage the dynamic fd arrays in the process files_struct.
*/
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/time.h>
@ -432,3 +433,63 @@ struct files_struct init_files = {
},
.file_lock = __SPIN_LOCK_UNLOCKED(init_task.file_lock),
};
/*
* allocate a file descriptor, mark it busy.
*/
int alloc_fd(unsigned start, unsigned flags)
{
struct files_struct *files = current->files;
unsigned int fd;
int error;
struct fdtable *fdt;
spin_lock(&files->file_lock);
repeat:
fdt = files_fdtable(files);
fd = start;
if (fd < files->next_fd)
fd = files->next_fd;
if (fd < fdt->max_fds)
fd = find_next_zero_bit(fdt->open_fds->fds_bits,
fdt->max_fds, fd);
error = expand_files(files, fd);
if (error < 0)
goto out;
/*
* If we needed to expand the fs array we
* might have blocked - try again.
*/
if (error)
goto repeat;
if (start <= files->next_fd)
files->next_fd = fd + 1;
FD_SET(fd, fdt->open_fds);
if (flags & O_CLOEXEC)
FD_SET(fd, fdt->close_on_exec);
else
FD_CLR(fd, fdt->close_on_exec);
error = fd;
#if 1
/* Sanity check */
if (rcu_dereference(fdt->fd[fd]) != NULL) {
printk(KERN_WARNING "alloc_fd: slot %d not NULL!\n", fd);
rcu_assign_pointer(fdt->fd[fd], NULL);
}
#endif
out:
spin_unlock(&files->file_lock);
return error;
}
int get_unused_fd(void)
{
return alloc_fd(0, 0);
}
EXPORT_SYMBOL(get_unused_fd);