linux-kernel - [PATCH 06/13] vfs: Remove next

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Date:   Fri, 28 Apr 2017 00:39:45 +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 06/13] vfs: Remove next_fd from fd alloc code path.

The IDR is used in file descriptor allocation code to
allocate new file descriptor so, no need of next_fd to
track next file descriptor.
Hence removing it from file descriptor allocation code path.

Signed-off-by: Sandhya Bankar <bankarsandhya512@...il.com>
Signed-off-by: Matthew Wilcox <mawilcox@...rosoft.com>
---
 fs/file.c               | 6 ------
 include/linux/fdtable.h | 1 -
 2 files changed, 7 deletions(-)

diff --git a/fs/file.c b/fs/file.c
index 1c000d8..da3a35b 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -294,7 +294,6 @@ struct files_struct *dup_fd(struct files_struct *oldf, int *errorp)
 	idr_init(&newf->fd_idr);
 	newf->resize_in_progress = false;
 	init_waitqueue_head(&newf->resize_wait);
-	newf->next_fd = 0;
 	new_fdt = &newf->fdtab;
 	new_fdt->max_fds = NR_OPEN_DEFAULT;
 	new_fdt->close_on_exec = newf->close_on_exec_init;
@@ -506,9 +505,6 @@ int __alloc_fd(struct files_struct *files,
 		goto out;
 	}
 
-	if (start <= files->next_fd)
-		files->next_fd = fd + 1;
-
 	fdt = files_fdtable(files);
 	__set_open_fd(fd, fdt);
 	if (flags & O_CLOEXEC)
@@ -538,8 +534,6 @@ static void __put_unused_fd(struct files_struct *files, unsigned int fd)
 {
 	struct fdtable *fdt = files_fdtable(files);
 	__clear_open_fd(fd, fdt);
-	if (fd < files->next_fd)
-		files->next_fd = fd;
 }
 
 void put_unused_fd(unsigned int fd)
diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h
index 4072f24..c2a53b6 100644
--- a/include/linux/fdtable.h
+++ b/include/linux/fdtable.h
@@ -58,7 +58,6 @@ struct files_struct {
    * written part on a separate cache line in SMP
    */
 	spinlock_t file_lock ____cacheline_aligned_in_smp;
-	unsigned int next_fd;
 	unsigned long close_on_exec_init[1];
 	unsigned long open_fds_init[1];
 	unsigned long full_fds_bits_init[1];
-- 
1.8.3.1