linux-kernel - [PATCH 07/13] vfs: Remove full_fds_bits from fd allocation code path.

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Date:   Fri, 28 Apr 2017 00:40:33 +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 07/13] vfs: Remove full_fds_bits from fd allocation code path.

The IDR has removed the need to have full_fds_bits hence removing it.

Signed-off-by: Sandhya Bankar <bankarsandhya512@...il.com>
Signed-off-by: Matthew Wilcox <mawilcox@...rosoft.com>
---
 fs/file.c               | 18 +-----------------
 include/linux/fdtable.h |  2 --
 2 files changed, 1 insertion(+), 19 deletions(-)

diff --git a/fs/file.c b/fs/file.c
index da3a35b..e8c6ada 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -56,9 +56,6 @@ static void free_fdtable_rcu(struct rcu_head *rcu)
 	__free_fdtable(container_of(rcu, struct fdtable, rcu));
 }
 
-#define BITBIT_NR(nr)	BITS_TO_LONGS(BITS_TO_LONGS(nr))
-#define BITBIT_SIZE(nr)	(BITBIT_NR(nr) * sizeof(long))
-
 /*
  * Copy 'count' fd bits from the old table to the new table and clear the extra
  * space if any.  This does not copy the file pointers.  Called with the files
@@ -75,11 +72,6 @@ static void copy_fd_bitmaps(struct fdtable *nfdt, struct fdtable *ofdt,
 	memset((char *)nfdt->open_fds + cpy, 0, set);
 	memcpy(nfdt->close_on_exec, ofdt->close_on_exec, cpy);
 	memset((char *)nfdt->close_on_exec + cpy, 0, set);
-
-	cpy = BITBIT_SIZE(count);
-	set = BITBIT_SIZE(nfdt->max_fds) - cpy;
-	memcpy(nfdt->full_fds_bits, ofdt->full_fds_bits, cpy);
-	memset((char *)nfdt->full_fds_bits + cpy, 0, set);
 }
 
 /*
@@ -124,14 +116,12 @@ static struct fdtable * alloc_fdtable(unsigned int nr)
 	fdt->max_fds = nr;
 
 	data = alloc_fdmem(max_t(size_t,
-				 2 * nr / BITS_PER_BYTE + BITBIT_SIZE(nr), L1_CACHE_BYTES));
+				 2 * nr / BITS_PER_BYTE, L1_CACHE_BYTES));
 	if (!data)
 		goto out_fdt;
 	fdt->open_fds = data;
 	data += nr / BITS_PER_BYTE;
 	fdt->close_on_exec = data;
-	data += nr / BITS_PER_BYTE;
-	fdt->full_fds_bits = data;
 
 	return fdt;
 
@@ -246,15 +236,11 @@ static inline void __clear_close_on_exec(unsigned int fd, struct fdtable *fdt)
 static inline void __set_open_fd(unsigned int fd, struct fdtable *fdt)
 {
 	__set_bit(fd, fdt->open_fds);
-	fd /= BITS_PER_LONG;
-	if (!~fdt->open_fds[fd])
-		__set_bit(fd, fdt->full_fds_bits);
 }
 
 static inline void __clear_open_fd(unsigned int fd, struct fdtable *fdt)
 {
 	__clear_bit(fd, fdt->open_fds);
-	__clear_bit(fd / BITS_PER_LONG, fdt->full_fds_bits);
 }
 
 static unsigned int count_open_files(struct fdtable *fdt)
@@ -298,7 +284,6 @@ struct files_struct *dup_fd(struct files_struct *oldf, int *errorp)
 	new_fdt->max_fds = NR_OPEN_DEFAULT;
 	new_fdt->close_on_exec = newf->close_on_exec_init;
 	new_fdt->open_fds = newf->open_fds_init;
-	new_fdt->full_fds_bits = newf->full_fds_bits_init;
 
 restart:
 	idr_copy_preload(&oldf->fd_idr, GFP_KERNEL);
@@ -472,7 +457,6 @@ struct files_struct init_files = {
 		.max_fds	= NR_OPEN_DEFAULT,
 		.close_on_exec	= init_files.close_on_exec_init,
 		.open_fds	= init_files.open_fds_init,
-		.full_fds_bits	= init_files.full_fds_bits_init,
 	},
 	.file_lock	= __SPIN_LOCK_UNLOCKED(init_files.file_lock),
 	.fd_idr		= IDR_INIT,
diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h
index c2a53b6..6bece35 100644
--- a/include/linux/fdtable.h
+++ b/include/linux/fdtable.h
@@ -26,7 +26,6 @@ struct fdtable {
 	unsigned int max_fds;
 	unsigned long *close_on_exec;
 	unsigned long *open_fds;
-	unsigned long *full_fds_bits;
 	struct rcu_head rcu;
 };
 
@@ -60,7 +59,6 @@ struct files_struct {
 	spinlock_t file_lock ____cacheline_aligned_in_smp;
 	unsigned long close_on_exec_init[1];
 	unsigned long open_fds_init[1];
-	unsigned long full_fds_bits_init[1];
 };
 
 struct file_operations;
-- 
1.8.3.1