Commit 1031bc58 authored by Dmitry Monakhov's avatar Dmitry Monakhov Committed by Al Viro
Browse files

lib/vsprintf: add %*pg format specifier 



This allow to directly print block_device name.
Currently one should use bdevname() with temporal char buffer.
This is very ineffective because bloat stack usage for deep IO call-traces

Example:
	%pg  ->    sda, sda1 or loop0p1

[AV: fixed a minor braino - position updates should not be dependent
upon having reached the of buffer]

Signed-off-by: default avatarDmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 424081f3

Documentation/printk-formats.txt

+6 −0
Original line number Diff line number Diff line
@@ -250,6 +250,12 @@ dentry names: 


	Passed by reference.



block_device names:



	%pg	sda, sda1 or loop0p1



	For printing name of block_device pointers.



struct va_format:



	%pV

lib/vsprintf.c

+29 −0
Original line number Diff line number Diff line
@@ -31,6 +31,9 @@ 
#include <linux/dcache.h>

#include <linux/cred.h>

#include <net/addrconf.h>

#ifdef CONFIG_BLOCK

#include <linux/blkdev.h>

#endif



#include <asm/page.h>		/* for PAGE_SIZE */

#include <asm/sections.h>	/* for dereference_function_descriptor() */
@@ -613,6 +616,26 @@ char *dentry_name(char *buf, char *end, const struct dentry *d, struct printf_sp 
	return buf;

}



#ifdef CONFIG_BLOCK

static noinline_for_stack

char *bdev_name(char *buf, char *end, struct block_device *bdev,

		struct printf_spec spec, const char *fmt)

{

	struct gendisk *hd = bdev->bd_disk;

	

	buf = string(buf, end, hd->disk_name, spec);

	if (bdev->bd_part->partno) {

		if (isdigit(hd->disk_name[strlen(hd->disk_name)-1])) {

			if (buf < end)

				*buf = 'p';

			buf++;

		}

		buf = number(buf, end, bdev->bd_part->partno, spec);

	}

	return buf;

}

#endif



static noinline_for_stack

char *symbol_string(char *buf, char *end, void *ptr,

		    struct printf_spec spec, const char *fmt)
@@ -1443,6 +1466,7 @@ int kptr_restrict __read_mostly; 
 *           (default assumed to be phys_addr_t, passed by reference)

 * - 'd[234]' For a dentry name (optionally 2-4 last components)

 * - 'D[234]' Same as 'd' but for a struct file

 * - 'g' For block_device name (gendisk + partition number)

 * - 'C' For a clock, it prints the name (Common Clock Framework) or address

 *       (legacy clock framework) of the clock

 * - 'Cn' For a clock, it prints the name (Common Clock Framework) or address
@@ -1600,6 +1624,11 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr, 
		return dentry_name(buf, end,

				   ((const struct file *)ptr)->f_path.dentry,

				   spec, fmt);

#ifdef CONFIG_BLOCK

	case 'g':

		return bdev_name(buf, end, ptr, spec, fmt);

#endif



	}

	spec.flags |= SMALL;

	if (spec.field_width == -1) {

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