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 <bankarsandhya...@gmail.com>
Signed-off-by: Matthew Wilcox <mawil...@microsoft.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

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