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debugfs: leave freeing a symlink body until inode eviction

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commit 0db59e5929 upstream.

As it is, we have debugfs_remove() racing with symlink traversals.
Supply ->evict_inode() and do freeing there - inode will remain
pinned until we are done with the symlink body.

And rip the idiocy with checking if dentry is positive right after
we'd verified debugfs_positive(), which is a stronger check...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
[bwh: Backported to 3.2:
 - Plumb in debugfs_super_operations, which we didn't previously define
 - Call truncate_inode_pages() instead of truncate_inode_pages_final()
 - Call end_writeback() instead of clear_inode()]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
This commit is contained in:
Al Viro
2015-02-21 22:05:11 -05:00
committed by Ben Hutchings
parent aafdaa379a
commit 915f4f86dd
1 changed files with 28 additions and 18 deletions
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46
fs/debugfs/inode.c
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@ -125,11 +125,30 @@ static inline int debugfs_positive(struct dentry *dentry)
return dentry->d_inode && !d_unhashed(dentry);
}
static void debugfs_evict_inode(struct inode *inode)
{
truncate_inode_pages(&inode->i_data, 0);
end_writeback(inode);
if (S_ISLNK(inode->i_mode))
kfree(inode->i_private);
}
static const struct super_operations debugfs_super_operations = {
.evict_inode = debugfs_evict_inode,
};
static int debug_fill_super(struct super_block *sb, void *data, int silent)
{
static struct tree_descr debug_files[] = {{""}};
int err;
return simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
err = simple_fill_super(sb, DEBUGFS_MAGIC, debug_files);
if (err)
return err;
sb->s_op = &debugfs_super_operations;
return 0;
}
static struct dentry *debug_mount(struct file_system_type *fs_type,
@ -312,23 +331,14 @@ static int __debugfs_remove(struct dentry *dentry, struct dentry *parent)
int ret = 0;
if (debugfs_positive(dentry)) {
if (dentry->d_inode) {
dget(dentry);
switch (dentry->d_inode->i_mode & S_IFMT) {
case S_IFDIR:
ret = simple_rmdir(parent->d_inode, dentry);
break;
case S_IFLNK:
kfree(dentry->d_inode->i_private);
/* fall through */
default:
simple_unlink(parent->d_inode, dentry);
break;
}
if (!ret)
d_delete(dentry);
dput(dentry);
}
dget(dentry);
if (S_ISDIR(dentry->d_inode->i_mode))
ret = simple_rmdir(parent->d_inode, dentry);
else
simple_unlink(parent->d_inode, dentry);
if (!ret)
d_delete(dentry);
dput(dentry);
}
return ret;
}