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Commit 4b6ccca7 authored by Al Viro's avatar Al Viro
Browse files

add formats for dentry/file pathnames 



New formats: %p[dD][234]?.  The next pointer is interpreted as struct dentry *
or struct file * resp. ('d' => dentry, 'D' => file) and the last component(s)
of pathname are printed (%pd => just the last one, %pd2 => the last two, etc.)

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent cffe78d9

Documentation/printk-formats.txt

+9 −0
Original line number Diff line number Diff line
@@ -168,6 +168,15 @@ UUID/GUID addresses: 
	Where no additional specifiers are used the default little endian

	order with lower case hex characters will be printed.



dentry names:

	%pd{,2,3,4}

	%pD{,2,3,4}



	For printing dentry name; if we race with d_move(), the name might be

	a mix of old and new ones, but it won't oops.  %pd dentry is a safer

	equivalent of %s dentry->d_name.name we used to use, %pd<n> prints

	n last components.  %pD does the same thing for struct file.



struct va_format:



	%pV

lib/vsprintf.c

+82 −0
Original line number Diff line number Diff line
@@ -26,6 +26,7 @@ 
#include <linux/math64.h>

#include <linux/uaccess.h>

#include <linux/ioport.h>

#include <linux/dcache.h>

#include <net/addrconf.h>



#include <asm/page.h>		/* for PAGE_SIZE */
@@ -532,6 +533,81 @@ char *string(char *buf, char *end, const char *s, struct printf_spec spec) 
	return buf;

}



static void widen(char *buf, char *end, unsigned len, unsigned spaces)

{

	size_t size;

	if (buf >= end)	/* nowhere to put anything */

		return;

	size = end - buf;

	if (size <= spaces) {

		memset(buf, ' ', size);

		return;

	}

	if (len) {

		if (len > size - spaces)

			len = size - spaces;

		memmove(buf + spaces, buf, len);

	}

	memset(buf, ' ', spaces);

}



static noinline_for_stack

char *dentry_name(char *buf, char *end, const struct dentry *d, struct printf_spec spec,

		  const char *fmt)

{

	const char *array[4], *s;

	const struct dentry *p;

	int depth;

	int i, n;



	switch (fmt[1]) {

		case '2': case '3': case '4':

			depth = fmt[1] - '0';

			break;

		default:

			depth = 1;

	}



	rcu_read_lock();

	for (i = 0; i < depth; i++, d = p) {

		p = ACCESS_ONCE(d->d_parent);

		array[i] = ACCESS_ONCE(d->d_name.name);

		if (p == d) {

			if (i)

				array[i] = "";

			i++;

			break;

		}

	}

	s = array[--i];

	for (n = 0; n != spec.precision; n++, buf++) {

		char c = *s++;

		if (!c) {

			if (!i)

				break;

			c = '/';

			s = array[--i];

		}

		if (buf < end)

			*buf = c;

	}

	rcu_read_unlock();

	if (n < spec.field_width) {

		/* we want to pad the sucker */

		unsigned spaces = spec.field_width - n;

		if (!(spec.flags & LEFT)) {

			widen(buf - n, end, n, spaces);

			return buf + spaces;

		}

		while (spaces--) {

			if (buf < end)

				*buf = ' ';

			++buf;

		}

	}

	return buf;

}



static noinline_for_stack

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

		    struct printf_spec spec, const char *fmt)
@@ -1253,6 +1329,12 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr, 
		spec.base = 16;

		return number(buf, end,

			      (unsigned long long) *((phys_addr_t *)ptr), spec);

	case 'd':

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

	case 'D':

		return dentry_name(buf, end,

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

				   spec, fmt);

	}

	spec.flags |= SMALL;

	if (spec.field_width == -1) {