From: Eric Sandeen Subject: [PATCH, RFC] ext4: add ioctl to force 32-bit hashes from indexed dirs Date: Thu, 28 Mar 2013 11:14:06 -0500 Message-ID: <51546C4E.9010903@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Anand Avati To: ext4 development Return-path: Received: from mx1.redhat.com ([209.132.183.28]:62806 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756213Ab3C1QOH (ORCPT ); Thu, 28 Mar 2013 12:14:07 -0400 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r2SGE7XU013631 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Thu, 28 Mar 2013 12:14:07 -0400 Sender: linux-ext4-owner@vger.kernel.org List-ID: This adds a new ioctl, EXT4_IOC_32BITHASH, which allows a userspace application to request 32-bit rather than 64-bit hashes from readdir on an indexed / dx / htree directory. Gluster had been relying on the top bits of the d_off being free; there are some reports that filling all 64 bits breaks Samba as well. The infrastructure to return 32-bit hashes already exists; NFS can turn it on, and it's turned on for 32-bit processes as well. So it's just a matter of flipping on the f_mode flag before readdir starts. Care needs to be taken that we don't change the FMODE flag after readdir has been started, so we make sure that filp->private_data has not yet been set before we set the flag (Thanks Zach!). Pre-submission-fixes-by: Zach Brown Signed-off-by: Eric Sandeen --- diff --git a/fs/ext4/dir.c b/fs/ext4/dir.c index d8cd1f0..5e3a316 100644 --- a/fs/ext4/dir.c +++ b/fs/ext4/dir.c @@ -39,7 +39,7 @@ static int ext4_dx_readdir(struct file *filp, * * Return 1 if it is a dx dir, 0 if not */ -static int is_dx_dir(struct inode *inode) +int is_dx_dir(struct inode *inode) { struct super_block *sb = inode->i_sb; diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 3b83cd6..63e922e 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -614,6 +614,7 @@ enum { /* note ioctl 10 reserved for an early version of the FIEMAP ioctl */ /* note ioctl 11 reserved for filesystem-independent FIEMAP ioctl */ #define EXT4_IOC_ALLOC_DA_BLKS _IO('f', 12) +#define EXT4_IOC_32BITHASH _IOW('f', 13, long) #define EXT4_IOC_MOVE_EXT _IOWR('f', 15, struct move_extent) #define EXT4_IOC_RESIZE_FS _IOW('f', 16, __u64) @@ -1953,6 +1954,7 @@ extern unsigned ext4_num_overhead_clusters(struct super_block *sb, ext4_fsblk_t ext4_inode_to_goal_block(struct inode *); /* dir.c */ +extern int is_dx_dir(struct inode *inode); extern int __ext4_check_dir_entry(const char *, unsigned int, struct inode *, struct file *, struct ext4_dir_entry_2 *, diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c index 721f4d3..f226373 100644 --- a/fs/ext4/ioctl.c +++ b/fs/ext4/ioctl.c @@ -356,7 +356,41 @@ group_add_out: mnt_drop_write_file(filp); return err; } + case EXT4_IOC_32BITHASH: { + __u32 hash32bits; + int err = 0; + if (get_user(hash32bits, (int __user *) arg)) + return -EFAULT; + + /* Serialize with readdir */ + if ((err = mutex_lock_killable(&inode->i_mutex))) + return err; + + /* protect f_mode */ + spin_lock(&filp->f_lock); + + /* Only valid for htree directories */ + if (!S_ISDIR(inode->i_mode) || !is_dx_dir(inode)) { + err = -EINVAL; + goto out_32bithash; + } + + /* Have we already started readir on this dx dir? */ + if (filp->private_data) { + err = -EINVAL; + goto out_32bithash; + } + + if (hash32bits) + filp->f_mode |= FMODE_32BITHASH; + else + filp->f_mode &= ~FMODE_32BITHASH; +out_32bithash: + spin_unlock(&filp->f_lock); + mutex_unlock(&inode->i_mutex); + return err; + } case EXT4_IOC_RESIZE_FS: { ext4_fsblk_t n_blocks_count; struct super_block *sb = inode->i_sb;