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

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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: Jens Axboe <jaxboe@fusionio.com>
This commit is contained in:
Jens Axboe 2010-06-03 14:54:39 +02:00
parent 419f8367ea
commit ff9da691c0
3 changed files with 49 additions and 17 deletions
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54
fs/pipe.c
View File

@ -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:

4
include/linux/pipe_fs_i.h
View File

@ -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);

8
kernel/sysctl.c
View File

@ -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