um: resurrect the right variant of mconsole_proc()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 21 insertions, 78 deletions

diff --git a/arch/um/drivers/mconsole_kern.c b/arch/um/drivers/mconsole_kern.c
index 664a60e8dfb4..495e5a725aa1 100644
--- a/arch/um/drivers/mconsole_kern.c
+++ b/arch/um/drivers/mconsole_kern.c
@@ -21,6 +21,9 @@
 #include <linux/un.h>
 #include <linux/workqueue.h>
 #include <linux/mutex.h>
+#include <linux/fs.h>
+#include <linux/mount.h>
+#include <linux/file.h>
 #include <asm/uaccess.h>
 #include <asm/switch_to.h>
 
@@ -118,90 +121,38 @@ void mconsole_log(struct mc_request *req)
         mconsole_reply(req, "", 0, 0);
 }
 
-/* This is a more convoluted version of mconsole_proc, which has some stability
- * problems; however, we need it fixed, because it is expected that UML users
- * mount HPPFS instead of procfs on /proc. And we want mconsole_proc to still
- * show the real procfs content, not the ones from hppfs.*/
-#if 0
 void mconsole_proc(struct mc_request *req)
 {
         struct vfsmount *mnt = current->nsproxy->pid_ns->proc_mnt;
-        struct file *file;
-        int n;
-        char *ptr = req->request.data, *buf;
-        mm_segment_t old_fs = get_fs();
-
-        ptr += strlen("proc");
-        ptr = skip_spaces(ptr);
-
-        file = file_open_root(mnt->mnt_root, mnt, ptr, O_RDONLY);
-        if (IS_ERR(file)) {
-                mconsole_reply(req, "Failed to open file", 1, 0);
-                goto out;
-        }
-
-        buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
-        if (buf == NULL) {
-                mconsole_reply(req, "Failed to allocate buffer", 1, 0);
-                goto out_fput;
-        }
-
-        if (file->f_op->read) {
-                do {
-                        loff_t pos;
-                        set_fs(KERNEL_DS);
-                        n = vfs_read(file, buf, PAGE_SIZE - 1, &pos);
-                        file_pos_write(file, pos);
-                        set_fs(old_fs);
-                        if (n >= 0) {
-                                buf[n] = '\0';
-                                mconsole_reply(req, buf, 0, (n > 0));
-                        }
-                        else {
-                                mconsole_reply(req, "Read of file failed",
-                                               1, 0);
-                                goto out_free;
-                        }
-                } while (n > 0);
-        }
-        else mconsole_reply(req, "", 0, 0);
-
- out_free:
-        kfree(buf);
- out_fput:
-        fput(file);
- out: ;
-}
-#endif
-
-void mconsole_proc(struct mc_request *req)
-{
-        char path[64];
         char *buf;
         int len;
-        int fd;
+        struct file *file;
         int first_chunk = 1;
         char *ptr = req->request.data;
 
         ptr += strlen("proc");
         ptr = skip_spaces(ptr);
-        snprintf(path, sizeof(path), "/proc/%s", ptr);
 
-        fd = sys_open(path, 0, 0);
-        if (fd < 0) {
+        file = file_open_root(mnt->mnt_root, mnt, ptr, O_RDONLY);
+        if (IS_ERR(file)) {
                 mconsole_reply(req, "Failed to open file", 1, 0);
-                printk(KERN_ERR "open %s: %d\n",path,fd);
+                printk(KERN_ERR "open /proc/%s: %ld\n", ptr, PTR_ERR(file));
                 goto out;
         }
 
         buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
         if (buf == NULL) {
                 mconsole_reply(req, "Failed to allocate buffer", 1, 0);
-                goto out_close;
+                goto out_fput;
         }
 
-        for (;;) {
-                len = sys_read(fd, buf, PAGE_SIZE-1);
+        do {
+                loff_t pos;
+                mm_segment_t old_fs = get_fs();
+                set_fs(KERNEL_DS);
+                len = vfs_read(file, buf, PAGE_SIZE - 1, &pos);
+                set_fs(old_fs);
+                file->f_pos = pos;
                 if (len < 0) {
                         mconsole_reply(req, "Read of file failed", 1, 0);
                         goto out_free;
@@ -211,22 +162,14 @@ void mconsole_proc(struct mc_request *req)
                         mconsole_reply(req, "\n", 0, 1);
                         first_chunk = 0;
                 }
-                if (len == PAGE_SIZE-1) {
-                        buf[len] = '\0';
-                        mconsole_reply(req, buf, 0, 1);
-                } else {
-                        buf[len] = '\0';
-                        mconsole_reply(req, buf, 0, 0);
-                        break;
-                }
-        }
-
+                buf[len] = '\0';
+                mconsole_reply(req, buf, 0, (len > 0));
+        } while (len > 0);
  out_free:
         kfree(buf);
- out_close:
-        sys_close(fd);
- out:
-        /* nothing */;
+ out_fput:
+        fput(file);
+ out: ;
 }
 
 #define UML_MCONSOLE_HELPTEXT \