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vfs: make follow_link check RCU safe

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This will allow this code to be used in RCU mode.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Miklos Szeredi
2012-05-21 17:30:09 +02:00
committed by Al Viro
parent decf340087
commit d45ea86792
1 changed files with 10 additions and 2 deletions
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12
fs/namei.c
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@@ -2201,6 +2201,7 @@ static struct file *do_last(struct nameidata *nd, struct path *path,
int acc_mode = op->acc_mode; int acc_mode = op->acc_mode;
struct file *filp; struct file *filp;
struct inode *inode; struct inode *inode;
int symlink_ok = 0;
int error; int error;
nd->flags &= ~LOOKUP_PARENT; nd->flags &= ~LOOKUP_PARENT;
@@ -2232,7 +2233,6 @@ static struct file *do_last(struct nameidata *nd, struct path *path,
} }
if (!(open_flag & O_CREAT)) { if (!(open_flag & O_CREAT)) {
int symlink_ok = 0;
if (nd->last.name[nd->last.len]) if (nd->last.name[nd->last.len])
nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW)) if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW))
@@ -2364,8 +2364,16 @@ static struct file *do_last(struct nameidata *nd, struct path *path,
if (!inode) if (!inode)
goto exit_dput; goto exit_dput;
if (inode->i_op->follow_link) if (should_follow_link(inode, !symlink_ok)) {
if (nd->flags & LOOKUP_RCU) {
if (unlikely(unlazy_walk(nd, path->dentry))) {
error = -ECHILD;
goto exit;
}
}
BUG_ON(inode != path->dentry->d_inode);
return NULL; return NULL;
}
path_to_nameidata(path, nd); path_to_nameidata(path, nd);
nd->inode = inode; nd->inode = inode;