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-rw-r--r--Documentation/printk-formats.txt9
-rw-r--r--lib/vsprintf.c82
2 files changed, 91 insertions, 0 deletions
diff --git a/Documentation/printk-formats.txt b/Documentation/printk-formats.txt
index 3e8cb73ac43c..9552a3299ec9 100644
--- a/Documentation/printk-formats.txt
+++ b/Documentation/printk-formats.txt
@@ -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
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 739a36366b79..26559bdb4c49 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -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) {

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