| From | lizf@kernel ... | Subject | [PATCH 3.4 046/172] debugfs: leave freeing a symlink body until inode eviction | Date | Tue, 16 Jun 2015 16:35:00 +0800 |
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From: Al Viro <viro@zeniv.linux.org.uk>
3.4.108-rc1 review patch. If anyone has any objections, please let me know.
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commit 0db59e59299f0b67450c5db21f7f316c8fb04e84 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> [lizf: Backported to 3.4: - call end_writeback() instead of clear_inode() - call truncate_inode_pages() instead of truncate_inode_pages_final()] Signed-off-by: Zefan Li <lizefan@huawei.com> --- fs/debugfs/inode.c | 34 +++++++++++++++++----------------- 1 file changed, 17 insertions(+), 17 deletions(-)
diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c index 47d64e9..7b65755 100644 --- a/fs/debugfs/inode.c +++ b/fs/debugfs/inode.c @@ -238,10 +238,19 @@ static int debugfs_show_options(struct seq_file *m, struct dentry *root) return 0; } +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 = { .statfs = simple_statfs, .remount_fs = debugfs_remount, .show_options = debugfs_show_options, + .evict_inode = debugfs_evict_inode, }; static int debug_fill_super(struct super_block *sb, void *data, int silent) @@ -459,23 +468,14 @@ 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; } -- 1.9.1
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