linux-ext4 - [PATCH 5/6] ext4: Drop i_state_flags on architectures with 64-bit longs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1294189270-16733-6-git-send-email-tytso@mit.edu>
Date:	Tue,  4 Jan 2011 20:01:09 -0500
From:	Theodore Ts'o <tytso@....edu>
To:	Ext4 Developers List <linux-ext4@...r.kernel.org>
Cc:	Theodore Ts'o <tytso@....edu>
Subject: [PATCH 5/6] ext4: Drop i_state_flags on architectures with 64-bit longs

We can store the dynamic inode state flags in the high bits of
EXT4_I(inode)->i_flags, and eliminate i_state_flags.  This saves 8
bytes from the size of ext4_inode_info structure, which when
multiplied by the number of the number of in the inode cache, can save
a lot of memory.

Signed-off-by: "Theodore Ts'o" <tytso@....edu>
---
 fs/ext4/ext4.h   |   20 ++++++++++++++------
 fs/ext4/ialloc.c |    2 +-
 fs/ext4/inode.c  |    4 ++--
 3 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 50e3d24..8a2603d 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -764,7 +764,9 @@ struct ext4_inode_info {
 	 */
 	ext4_group_t	i_block_group;
 	ext4_lblk_t	i_dir_start_lookup;
+#if (BITS_PER_LONG < 64)
 	unsigned long	i_state_flags;		/* Dynamic state flags */
+#endif
 	unsigned long	i_flags;
 
 #ifdef CONFIG_EXT4_FS_XATTR
@@ -1239,22 +1241,28 @@ enum {
 	EXT4_STATE_DELALLOC_RESERVED,	/* blks already reserved for delalloc */
 };
 
-#define EXT4_INODE_BIT_FNS(name, field)					\
+#define EXT4_INODE_BIT_FNS(name, field, offset)				\
 static inline int ext4_test_inode_##name(struct inode *inode, int bit)	\
 {									\
-	return test_bit(bit, &EXT4_I(inode)->i_##field);		\
+	return test_bit(bit + (offset), &EXT4_I(inode)->i_##field);	\
 }									\
 static inline void ext4_set_inode_##name(struct inode *inode, int bit)	\
 {									\
-	set_bit(bit, &EXT4_I(inode)->i_##field);			\
+	set_bit(bit + (offset), &EXT4_I(inode)->i_##field);		\
 }									\
 static inline void ext4_clear_inode_##name(struct inode *inode, int bit) \
 {									\
-	clear_bit(bit, &EXT4_I(inode)->i_##field);			\
+	clear_bit(bit + (offset), &EXT4_I(inode)->i_##field);		\
 }
 
-EXT4_INODE_BIT_FNS(flag, flags)
-EXT4_INODE_BIT_FNS(state, state_flags)
+EXT4_INODE_BIT_FNS(flag, flags, 0)
+#if (BITS_PER_LONG < 64)
+EXT4_INODE_BIT_FNS(state, state_flags, 0)
+#define EXT4_CLEAR_STATE_FLAGS(ei)	(ei)->i_state_flags = 0
+#else
+EXT4_INODE_BIT_FNS(state, flags, 32)
+#define EXT4_CLEAR_STATE_FLAGS(ei)	(ei)->i_flags = 0
+#endif
 #else
 /* Assume that user mode programs are passing in an ext4fs superblock, not
  * a kernel struct super_block.  This will allow us to call the feature-test
diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index 1ce240a..67b6779 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -1009,6 +1009,7 @@ got:
 	 * extent flag on newly created directory and file only if -o extent
 	 * mount option is specified
 	 */
+	EXT4_CLEAR_STATE_FLAGS(ei);
 	ei->i_flags =
 		ext4_mask_flags(mode, EXT4_I(dir)->i_flags & EXT4_FL_INHERITED);
 	ei->i_file_acl = 0;
@@ -1027,7 +1028,6 @@ got:
 	inode->i_generation = sbi->s_next_generation++;
 	spin_unlock(&sbi->s_next_gen_lock);
 
-	ei->i_state_flags = 0;
 	ext4_set_inode_state(inode, EXT4_STATE_NEW);
 
 	ei->i_extra_isize = EXT4_SB(sb)->s_want_extra_isize;
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 3ae8313..2d60028 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4868,7 +4868,7 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino)
 	}
 	inode->i_nlink = le16_to_cpu(raw_inode->i_links_count);
 
-	ei->i_state_flags = 0;
+	EXT4_CLEAR_STATE_FLAGS(ei);
 	ei->i_dir_start_lookup = 0;
 	ei->i_dtime = le32_to_cpu(raw_inode->i_dtime);
 	/* We now have enough fields to check if the inode was active or not.
@@ -5127,7 +5127,7 @@ static int ext4_do_update_inode(handle_t *handle,
 	if (ext4_inode_blocks_set(handle, raw_inode, ei))
 		goto out_brelse;
 	raw_inode->i_dtime = cpu_to_le32(ei->i_dtime);
-	raw_inode->i_flags = cpu_to_le32(ei->i_flags);
+	raw_inode->i_flags = cpu_to_le32(ei->i_flags & 0xFFFFFFFF);
 	if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
 	    cpu_to_le32(EXT4_OS_HURD))
 		raw_inode->i_file_acl_high =
-- 
1.7.3.1

--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html