On Mon 01-04-13 10:33:41, Eric Sandeen wrote:
> 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!).
OK, I'm happy with this patch. So if Samba people confirm they are really
going to use it, I'll merge the patch.
Honza
> Pre-submission-fixes-by: Zach Brown <zab@xxxxxxxxxx>
> Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx>
> ---
>
> V2:
> fix "readir" typo
> rename goto target to *_out like others
> remove parameter; we can't really ever turn this back off once it's used.
> closing and reopening is the only way to get back to 64 bit hashes.
>
> V3:
> return -ENOTDIR if the target is not a directory
>
>
>
>
> 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..f3018f4 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 _IO('f', 13)
>
> /*
> * 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..a7d2b0a 100644
> --- a/fs/ext3/ioctl.c
> +++ b/fs/ext3/ioctl.c
> @@ -251,6 +251,39 @@ group_add_out:
> mnt_drop_write_file(filp);
> return err;
> }
> + case EXT3_IOC_32BITHASH: {
> + int err = 0;
> +
> + /* 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)) {
> + err = -ENOTDIR;
> + goto hash32bits_out;
> + }
> +
> + if (!is_dx_dir(inode)) {
> + err = -EINVAL;
> + goto hash32bits_out;
> + }
> +
> + /* Have we already started readdir on this dx dir? */
> + if (filp->private_data) {
> + err = -EINVAL;
> + goto hash32bits_out;
> + }
> +
> + filp->f_mode |= FMODE_32BITHASH;
> +hash32bits_out:
> + spin_unlock(&filp->f_lock);
> + mutex_unlock(&inode->i_mutex);
> + return err;
> + }
> case FITRIM: {
>
> struct super_block *sb = inode->i_sb;
>
>
>
--
Jan Kara <jack@xxxxxxx>
SUSE Labs, CR
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