[PATCH 06/13] vfs: Remove next_fd from fd alloc code path.

From: Sandhya Bankar
Date: Sat Apr 29 2017 - 03:43:15 EST


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@xxxxxxxxx>
Signed-off-by: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
---
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