From: Theodore Ts'o <tytso@mit.edu> Date: Tue, 2 Nov 2010 13:34:50 +0000 (-0400) Subject: ext4: Remove useless spinlock in ext4_getattr() X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=eb8abb927ae2fd1730e24ea94cd9527f3c086292;p=openwrt%2Fstaging%2Fblogic.git ext4: Remove useless spinlock in ext4_getattr() Linus noted, and complained to me, that doing while lots of "git diff"'s of kernel sources, these spinlocks were responsible for 27% of the spinlock cost on his two-processor system as reported by perf. Git was doing lots of parallel stats, and this was putting a lot of pressure on ext4_getattr(). A spinlock to protect a single memory-to-memory copy is pointless, so remove it. Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> --- diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 191616470466..4d78342f3bf0 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -5410,9 +5410,7 @@ int ext4_getattr(struct vfsmount *mnt, struct dentry *dentry, * will return the blocks that include the delayed allocation * blocks for this file. */ - spin_lock(&EXT4_I(inode)->i_block_reservation_lock); delalloc_blocks = EXT4_I(inode)->i_reserved_data_blocks; - spin_unlock(&EXT4_I(inode)->i_block_reservation_lock); stat->blocks += (delalloc_blocks << inode->i_sb->s_blocksize_bits)>>9; return 0;