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Commit ff9da691 authored by Jens Axboe's avatar Jens Axboe
Browse files

pipe: change /proc/sys/fs/pipe-max-pages to byte sized interface 



This changes the interface to be based on bytes instead. The API
matches that of F_SETPIPE_SZ in that it rounds up the passed in
size so that the resulting page array is a power-of-2 in size.

The proc file is renamed to /proc/sys/fs/pipe-max-size to
reflect this change.

Signed-off-by: default avatarJens Axboe <jaxboe@fusionio.com>
parent 419f8367

fs/pipe.c

+42 −12
Original line number Diff line number Diff line
@@ -26,9 +26,14 @@ 


/*

 * The max size that a non-root user is allowed to grow the pipe. Can

 * be set by root in /proc/sys/fs/pipe-max-pages

 * be set by root in /proc/sys/fs/pipe-max-size

 */

unsigned int pipe_max_pages = PIPE_DEF_BUFFERS * 16;

unsigned int pipe_max_size = 1048576;



/*

 * Minimum pipe size, as required by POSIX

 */

unsigned int pipe_min_size = PAGE_SIZE;



/*

 * We use a start+len construction, which provides full use of the
@@ -1156,6 +1161,35 @@ static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long nr_pages) 
	return nr_pages * PAGE_SIZE;

}



/*

 * Currently we rely on the pipe array holding a power-of-2 number

 * of pages.

 */

static inline unsigned int round_pipe_size(unsigned int size)

{

	unsigned long nr_pages;



	nr_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;

	return roundup_pow_of_two(nr_pages) << PAGE_SHIFT;

}



/*

 * This should work even if CONFIG_PROC_FS isn't set, as proc_dointvec_minmax

 * will return an error.

 */

int pipe_proc_fn(struct ctl_table *table, int write, void __user *buf,

		 size_t *lenp, loff_t *ppos)

{

	int ret;



	ret = proc_dointvec_minmax(table, write, buf, lenp, ppos);

	if (ret < 0 || !write)

		return ret;



	pipe_max_size = round_pipe_size(pipe_max_size);

	return ret;

}



long pipe_fcntl(struct file *file, unsigned int cmd, unsigned long arg)

{

	struct pipe_inode_info *pipe;
@@ -1169,23 +1203,19 @@ long pipe_fcntl(struct file *file, unsigned int cmd, unsigned long arg) 


	switch (cmd) {

	case F_SETPIPE_SZ: {

		unsigned long nr_pages;

		unsigned int size, nr_pages;



		/*

		 * Currently the array must be a power-of-2 size, so adjust

		 * upwards if needed.

		 */

		nr_pages = (arg + PAGE_SIZE - 1) >> PAGE_SHIFT;

		nr_pages = roundup_pow_of_two(nr_pages);

		size = round_pipe_size(arg);

		nr_pages = size >> PAGE_SHIFT;



		if (!capable(CAP_SYS_RESOURCE) && nr_pages > pipe_max_pages) {

		if (!capable(CAP_SYS_RESOURCE) && size > pipe_max_size) {

			ret = -EPERM;

			goto out;

		} else if (nr_pages < 1) {

		} else if (nr_pages < PAGE_SIZE) {

			ret = -EINVAL;

			goto out;

		}

		ret = pipe_set_size(pipe, arg);

		ret = pipe_set_size(pipe, nr_pages);

		break;

		}

	case F_GETPIPE_SZ:

include/linux/pipe_fs_i.h

+3 −1
Original line number Diff line number Diff line
@@ -139,7 +139,9 @@ void pipe_lock(struct pipe_inode_info *); 
void pipe_unlock(struct pipe_inode_info *);

void pipe_double_lock(struct pipe_inode_info *, struct pipe_inode_info *);



extern unsigned int pipe_max_pages;

extern unsigned int pipe_max_size, pipe_min_size;

int pipe_proc_fn(struct ctl_table *, int, void __user *, size_t *, loff_t *);





/* Drop the inode semaphore and wait for a pipe event, atomically */

void pipe_wait(struct pipe_inode_info *pipe);

kernel/sysctl.c

+4 −4
Original line number Diff line number Diff line
@@ -1471,12 +1471,12 @@ static struct ctl_table fs_table[] = { 
	},

#endif

	{

		.procname	= "pipe-max-pages",

		.data		= &pipe_max_pages,

		.procname	= "pipe-max-size",

		.data		= &pipe_max_size,

		.maxlen		= sizeof(int),

		.mode		= 0644,

		.proc_handler	= &proc_dointvec_minmax,

		.extra1		= &two,

		.proc_handler	= &pipe_proc_fn,

		.extra1		= &pipe_min_size,

	},

/*

 * NOTE: do not add new entries to this table unless you have read