From 96fdc72ddfe8aa3eb1f51e78cc13babefbf26dda Mon Sep 17 00:00:00 2001 From: Davide Libenzi Date: Tue, 16 Oct 2007 23:30:19 -0700 Subject: anon-inodes use open coded atomic_inc for the shared inode Since we know the shared inode count is always >0, we can avoid igrab() and use an open coded atomic_inc(). This also fixes a bug noticed by Yan Zheng : were checking for an IS_ERR() return from igrab(), but it actually returns NULL on error. Signed-off-by: Davide Libenzi Cc: Yan Zheng Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/anon_inodes.c | 25 ++++++++++++------------- 1 file changed, 12 insertions(+), 13 deletions(-) (limited to 'fs') diff --git a/fs/anon_inodes.c b/fs/anon_inodes.c index b4a75880f6fd..23321889d9b0 100644 --- a/fs/anon_inodes.c +++ b/fs/anon_inodes.c @@ -76,7 +76,6 @@ int anon_inode_getfd(int *pfd, struct inode **pinode, struct file **pfile, { struct qstr this; struct dentry *dentry; - struct inode *inode; struct file *file; int error, fd; @@ -86,15 +85,9 @@ int anon_inode_getfd(int *pfd, struct inode **pinode, struct file **pfile, if (!file) return -ENFILE; - inode = igrab(anon_inode_inode); - if (IS_ERR(inode)) { - error = PTR_ERR(inode); - goto err_put_filp; - } - error = get_unused_fd(); if (error < 0) - goto err_iput; + goto err_put_filp; fd = error; /* @@ -108,14 +101,22 @@ int anon_inode_getfd(int *pfd, struct inode **pinode, struct file **pfile, dentry = d_alloc(anon_inode_mnt->mnt_sb->s_root, &this); if (!dentry) goto err_put_unused_fd; + + /* + * We know the anon_inode inode count is always greater than zero, + * so we can avoid doing an igrab() and we can use an open-coded + * atomic_inc(). + */ + atomic_inc(&anon_inode_inode->i_count); + dentry->d_op = &anon_inodefs_dentry_operations; /* Do not publish this dentry inside the global dentry hash table */ dentry->d_flags &= ~DCACHE_UNHASHED; - d_instantiate(dentry, inode); + d_instantiate(dentry, anon_inode_inode); file->f_path.mnt = mntget(anon_inode_mnt); file->f_path.dentry = dentry; - file->f_mapping = inode->i_mapping; + file->f_mapping = anon_inode_inode->i_mapping; file->f_pos = 0; file->f_flags = O_RDWR; @@ -127,14 +128,12 @@ int anon_inode_getfd(int *pfd, struct inode **pinode, struct file **pfile, fd_install(fd, file); *pfd = fd; - *pinode = inode; + *pinode = anon_inode_inode; *pfile = file; return 0; err_put_unused_fd: put_unused_fd(fd); -err_iput: - iput(inode); err_put_filp: put_filp(file); return error; -- cgit v1.2.2