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authorAl Viro <viro@zeniv.linux.org.uk>2011-06-20 10:52:57 -0400
committerAl Viro <viro@zeniv.linux.org.uk>2011-07-20 01:43:14 -0400
commit07b8ce1ee87d291ff564c02cf878fae973317a52 (patch)
tree94f07ed2b5d18aef71f1b28193375f88c0c947bc /fs/namei.c
parentf4d6ff89d8e54b68a4322388d26d518d6133fa4e (diff)
lockless get_write_access/deny_write_access
new helpers: atomic_inc_unless_negative()/atomic_dec_unless_positive() Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/namei.c')
-rw-r--r--fs/namei.c46
1 files changed, 0 insertions, 46 deletions
diff --git a/fs/namei.c b/fs/namei.c
index e04f15ae4b0..d286cbc3f3e 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -341,52 +341,6 @@ ok:
return security_inode_exec_permission(inode, flags);
}
-/*
- * get_write_access() gets write permission for a file.
- * put_write_access() releases this write permission.
- * This is used for regular files.
- * We cannot support write (and maybe mmap read-write shared) accesses and
- * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode
- * can have the following values:
- * 0: no writers, no VM_DENYWRITE mappings
- * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist
- * > 0: (i_writecount) users are writing to the file.
- *
- * Normally we operate on that counter with atomic_{inc,dec} and it's safe
- * except for the cases where we don't hold i_writecount yet. Then we need to
- * use {get,deny}_write_access() - these functions check the sign and refuse
- * to do the change if sign is wrong. Exclusion between them is provided by
- * the inode->i_lock spinlock.
- */
-
-int get_write_access(struct inode * inode)
-{
- spin_lock(&inode->i_lock);
- if (atomic_read(&inode->i_writecount) < 0) {
- spin_unlock(&inode->i_lock);
- return -ETXTBSY;
- }
- atomic_inc(&inode->i_writecount);
- spin_unlock(&inode->i_lock);
-
- return 0;
-}
-
-int deny_write_access(struct file * file)
-{
- struct inode *inode = file->f_path.dentry->d_inode;
-
- spin_lock(&inode->i_lock);
- if (atomic_read(&inode->i_writecount) > 0) {
- spin_unlock(&inode->i_lock);
- return -ETXTBSY;
- }
- atomic_dec(&inode->i_writecount);
- spin_unlock(&inode->i_lock);
-
- return 0;
-}
-
/**
* path_get - get a reference to a path
* @path: path to get the reference to