linux-kernel - [PATCH 09/13] vfs: Rewrite close

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Message-ID: <7453be343ca52991abe1820d834d2877ce1d7023.1493315290.git.bankarsandhya512@gmail.com>
Date:   Fri, 28 Apr 2017 00:42:05 +0530
From:   Sandhya Bankar <bankarsandhya512@...il.com>
To:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        viro@...iv.linux.org.uk, mawmilcox@...rosoft.com,
        keescook@...omium.org, adobriyan@...il.com, re.emese@...il.com,
        riel@...riel.com
Subject: [PATCH 09/13] vfs: Rewrite close_files()

Use the IDR iteration functionality instead of the open_fds bitmap to
call filp_close() for each open file.  Also make close_files() return
void, because it no longer uses the fdtable.

Signed-off-by: Sandhya Bankar <bankarsandhya512@...il.com>
Signed-off-by: Matthew Wilcox <mawilcox@...rosoft.com>
---
 fs/file.c | 37 +++++++++++--------------------------
 1 file changed, 11 insertions(+), 26 deletions(-)

diff --git a/fs/file.c b/fs/file.c
index 8d67968..8cd77c5 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -373,37 +373,21 @@ struct files_struct *dup_fd(struct files_struct *oldf, int *errorp)
 	return NULL;
 }
 
-static struct fdtable *close_files(struct files_struct * files)
+static void close_files(struct files_struct * files)
 {
 	/*
-	 * It is safe to dereference the fd table without RCU or
-	 * ->file_lock because this is the last reference to the
-	 * files structure.
+	 * No need for RCU or ->file_lock protection because
+	 * this is the last reference to the files structure.
 	 */
-	struct fdtable *fdt = rcu_dereference_raw(files->fdt);
-	unsigned int i, j = 0;
+	struct file *file;
+	int fd;
 
-	for (;;) {
-		unsigned long set;
-		i = j * BITS_PER_LONG;
-		if (i >= fdt->max_fds)
-			break;
-		set = fdt->open_fds[j++];
-		while (set) {
-			if (set & 1) {
-				struct file *file;
-				file = idr_remove(&files->fd_idr, i);
-				if (file) {
-					filp_close(file, files);
-					cond_resched_rcu_qs();
-				}
-			}
-			i++;
-			set >>= 1;
-		}
+	idr_for_each_entry(&files->fd_idr, file, fd) {
+		filp_close(file, files);
+		cond_resched_rcu_qs();
 	}
 
-	return fdt;
+	idr_destroy(&files->fd_idr);
 }
 
 struct files_struct *get_files_struct(struct task_struct *task)
@@ -422,7 +406,8 @@ struct files_struct *get_files_struct(struct task_struct *task)
 void put_files_struct(struct files_struct *files)
 {
 	if (atomic_dec_and_test(&files->count)) {
-		struct fdtable *fdt = close_files(files);
+		struct fdtable *fdt = rcu_dereference_raw(files->fdt);
+		close_files(files);
 
 		/* free the arrays if they are not embedded */
 		if (fdt != &files->fdtab)
-- 
1.8.3.1