acct: switch to __kernel_write()

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

fs/internal.h

@@ -131,7 +131,6 @@ extern long prune_dcache_sb(struct super_block *sb, unsigned long nr_to_scan,
 /*
  * read_write.c
  */
-extern ssize_t __kernel_write(struct file *, const char *, size_t, loff_t *);
 extern int rw_verify_area(int, struct file *, const loff_t *, size_t);
 
 /*

include/linux/fs.h

@@ -2335,6 +2335,7 @@ extern int do_pipe_flags(int *, int);
 
 extern int kernel_read(struct file *, loff_t, char *, unsigned long);
 extern ssize_t kernel_write(struct file *, const char *, size_t, loff_t);
+extern ssize_t __kernel_write(struct file *, const char *, size_t, loff_t *);
 extern struct file * open_exec(const char *);
  
 /* fs/dcache.c -- generic fs support functions */

kernel/acct.c

@@ -456,12 +456,16 @@ static void do_acct_process(struct bsd_acct_struct *acct,
 {
 	struct pacct_struct *pacct = &current->signal->pacct;
 	acct_t ac;
-	mm_segment_t fs;
 	unsigned long flim;
 	u64 elapsed, run_time;
 	struct tty_struct *tty;
 	const struct cred *orig_cred;
 
+	/*
+	 * Accounting records are not subject to resource limits.
+	 */
+	flim = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
+	current->signal->rlim[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY;
 	/* Perform file operations on behalf of whoever enabled accounting */
 	orig_cred = override_creds(file->f_cred);
 
@@ -536,25 +540,14 @@ static void do_acct_process(struct bsd_acct_struct *acct,
 	 * Get freeze protection. If the fs is frozen, just skip the write
 	 * as we could deadlock the system otherwise.
 	 */
-	if (!file_start_write_trylock(file))
-		goto out;
-	/*
-	 * Kernel segment override to datasegment and write it
-	 * to the accounting file.
-	 */
-	fs = get_fs();
-	set_fs(KERNEL_DS);
-	/*
-	 * Accounting records are not subject to resource limits.
-	 */
-	flim = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
-	current->signal->rlim[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY;
-	file->f_op->write(file, (char *)&ac,
-			       sizeof(acct_t), &file->f_pos);
-	current->signal->rlim[RLIMIT_FSIZE].rlim_cur = flim;
-	set_fs(fs);
+	if (file_start_write_trylock(file)) {
+		/* it's been opened O_APPEND, so position is irrelevant */
+		loff_t pos = 0;
+		__kernel_write(file, (char *)&ac, sizeof(acct_t), &pos);
 		file_end_write(file);
+	}
 out:
+	current->signal->rlim[RLIMIT_FSIZE].rlim_cur = flim;
 	revert_creds(orig_cred);
 }