Revert "proc: revert /proc/uptime to ->read_proc hook"

This reverts commit 6c87df37dcb9c6c33923707fa5191e0a65874d60.

proc files implemented through seq_file do pread(2) now.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>

1 files changed, 18 insertions, 20 deletions

diff --git a/fs/proc/uptime.c b/fs/proc/uptime.c
index df26aa88fa47..0c10a0b3f146 100644
--- a/fs/proc/uptime.c
+++ b/fs/proc/uptime.c
@@ -1,45 +1,43 @@
+#include <linux/fs.h>
 #include <linux/init.h>
 #include <linux/proc_fs.h>
 #include <linux/sched.h>
+#include <linux/seq_file.h>
 #include <linux/time.h>
 #include <asm/cputime.h>
 
-static int proc_calc_metrics(char *page, char **start, off_t off,
-                                 int count, int *eof, int len)
-{
-        if (len <= off + count)
-                *eof = 1;
-        *start = page + off;
-        len -= off;
-        if (len > count)
-                len = count;
-        if (len < 0)
-                len = 0;
-        return len;
-}
-
-static int uptime_read_proc(char *page, char **start, off_t off, int count,
-                            int *eof, void *data)
+static int uptime_proc_show(struct seq_file *m, void *v)
 {
         struct timespec uptime;
         struct timespec idle;
-        int len;
         cputime_t idletime = cputime_add(init_task.utime, init_task.stime);
 
         do_posix_clock_monotonic_gettime(&uptime);
         monotonic_to_bootbased(&uptime);
         cputime_to_timespec(idletime, &idle);
-        len = sprintf(page, "%lu.%02lu %lu.%02lu\n",
+        seq_printf(m, "%lu.%02lu %lu.%02lu\n",
                         (unsigned long) uptime.tv_sec,
                         (uptime.tv_nsec / (NSEC_PER_SEC / 100)),
                         (unsigned long) idle.tv_sec,
                         (idle.tv_nsec / (NSEC_PER_SEC / 100)));
-        return proc_calc_metrics(page, start, off, count, eof, len);
+        return 0;
 }
 
+static int uptime_proc_open(struct inode *inode, struct file *file)
+{
+        return single_open(file, uptime_proc_show, NULL);
+}
+
+static const struct file_operations uptime_proc_fops = {
+        .open           = uptime_proc_open,
+        .read           = seq_read,
+        .llseek         = seq_lseek,
+        .release        = single_release,
+};
+
 static int __init proc_uptime_init(void)
 {
-        create_proc_read_entry("uptime", 0, NULL, uptime_read_proc, NULL);
+        proc_create("uptime", 0, NULL, &uptime_proc_fops);
         return 0;
 }
 module_init(proc_uptime_init);