From: Eric Sandeen Subject: [PATCH, RFC] ext3: add ioctl to force 32-bit hashes from indexed dirs Date: Thu, 28 Mar 2013 11:25:17 -0500 Message-ID: <51546EED.8030507@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Anand Avati , Jan Kara To: ext4 development Return-path: Received: from mx1.redhat.com ([209.132.183.28]:33548 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753268Ab3C1Q0C (ORCPT ); Thu, 28 Mar 2013 12:26:02 -0400 Sender: linux-ext4-owner@vger.kernel.org List-ID: This adds a new ioctl, EXT3_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/ext3/dir.c b/fs/ext3/dir.c index 87eccbb..83df29f 100644 --- a/fs/ext3/dir.c +++ b/fs/ext3/dir.c @@ -47,7 +47,7 @@ static unsigned char get_dtype(struct super_block *sb, int filetype) * * 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/ext3/ext3.h b/fs/ext3/ext3.h index e85ff15..b88cf19 100644 --- a/fs/ext3/ext3.h +++ b/fs/ext3/ext3.h @@ -220,6 +220,7 @@ struct ext3_new_group_data { #endif #define EXT3_IOC_GETRSVSZ _IOR('f', 5, long) #define EXT3_IOC_SETRSVSZ _IOW('f', 6, long) +#define EXT3_IOC_32BITHASH _IOW('f', 13, long) /* * ioctl commands in 32 bit emulation @@ -1010,6 +1011,7 @@ extern void ext3_rsv_window_add(struct super_block *sb, struct ext3_reserve_wind extern int ext3_trim_fs(struct super_block *sb, struct fstrim_range *range); /* dir.c */ +extern int is_dx_dir(struct inode *inode); extern int ext3_check_dir_entry(const char *, struct inode *, struct ext3_dir_entry_2 *, struct buffer_head *, unsigned long); diff --git a/fs/ext3/ioctl.c b/fs/ext3/ioctl.c index 4d96e9a..aab217d 100644 --- a/fs/ext3/ioctl.c +++ b/fs/ext3/ioctl.c @@ -251,6 +251,41 @@ group_add_out: mnt_drop_write_file(filp); return err; } + case EXT3_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 FITRIM: { struct super_block *sb = inode->i_sb;