From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752382AbcL2C6h (ORCPT ); Wed, 28 Dec 2016 21:58:37 -0500 Received: from fieldses.org ([173.255.197.46]:39734 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752187AbcL2C6g (ORCPT ); Wed, 28 Dec 2016 21:58:36 -0500 Date: Wed, 28 Dec 2016 21:58:35 -0500 To: Richard Weinberger Cc: linux-mtd@lists.infradead.org, david@sigma-star.at, tytso@mit.edu, dedekind1@gmail.com, adrian.hunter@intel.com, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, adilger.kernel@dilger.ca, akpm@linux-foundation.org, linux-ext4@vger.kernel.org Subject: Re: [PATCH 3/6] ubifs: Use 64bit readdir cookies Message-ID: <20161229025835.GC21325@fieldses.org> References: <1480629741-18375-1-git-send-email-richard@nod.at> <1480629741-18375-4-git-send-email-richard@nod.at> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1480629741-18375-4-git-send-email-richard@nod.at> User-Agent: Mutt/1.5.21 (2010-09-15) From: bfields@fieldses.org (J. Bruce Fields) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Dec 01, 2016 at 11:02:18PM +0100, Richard Weinberger wrote: > This is the first step to support proper telldir/seekdir() > in UBIFS. > Let's report 64bit cookies in readdir(). The cookie is a combination > of the entry key plus the double hash value. Would it be possible to explain what that means in a little detail, for a ubifs-ignoramus? I'm just curious how it meets the requirements for nfs exports. --b. > > Signed-off-by: Richard Weinberger > --- > fs/ubifs/dir.c | 46 +++++++++++++++++++++++++++++++------------ > fs/ubifs/key.h | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > fs/ubifs/ubifs.h | 1 + > 3 files changed, 94 insertions(+), 12 deletions(-) > > diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c > index 883b2fdf51df..3b8c08dad75b 100644 > --- a/fs/ubifs/dir.c > +++ b/fs/ubifs/dir.c > @@ -539,7 +539,7 @@ static int ubifs_readdir(struct file *file, struct dir_context *ctx) > > dbg_gen("dir ino %lu, f_pos %#llx", dir->i_ino, ctx->pos); > > - if (ctx->pos > UBIFS_S_KEY_HASH_MASK || ctx->pos == 2) > + if (ctx->pos == 2) > /* > * The directory was seek'ed to a senseless position or there > * are no more entries. > @@ -594,7 +594,7 @@ static int ubifs_readdir(struct file *file, struct dir_context *ctx) > goto out; > } > > - ctx->pos = key_hash_flash(c, &dent->key); > + ctx->pos = key_get_dir_pos(c, file, dent); > file->private_data = dent; > } > > @@ -604,21 +604,43 @@ static int ubifs_readdir(struct file *file, struct dir_context *ctx) > * The directory was seek'ed to and is now readdir'ed. > * Find the entry corresponding to @ctx->pos or the closest one. > */ > - dent_key_init_hash(c, &key, dir->i_ino, ctx->pos); > - fname_len(&nm) = 0; > - dent = ubifs_tnc_next_ent(c, &key, &nm); > - if (IS_ERR(dent)) { > - err = PTR_ERR(dent); > - goto out; > + dent_key_init_hash(c, &key, dir->i_ino, > + key_get_hash_from_dir_pos(c, file, ctx->pos)); > + > + if (key_want_short_hash(file)) { > + err = -ENOENT; > + } else { > + dent = kmalloc(UBIFS_MAX_DENT_NODE_SZ, GFP_NOFS); > + if (!dent) { > + err = -ENOMEM; > + goto out; > + } > + > + err = ubifs_tnc_lookup_dh(c, &key, dent, > + key_get_cookie_from_dir_pos(c, ctx->pos)); > + } > + if (err) { > + kfree(dent); > + > + if (err < 0 && err != -ENOENT && err != -EOPNOTSUPP) > + goto out; > + > + fname_len(&nm) = 0; > + dent = ubifs_tnc_next_ent(c, &key, &nm); > + if (IS_ERR(dent)) { > + err = PTR_ERR(dent); > + goto out; > + } > } > - ctx->pos = key_hash_flash(c, &dent->key); > + > + ctx->pos = key_get_dir_pos(c, file, dent); > file->private_data = dent; > } > > while (1) { > - dbg_gen("feed '%s', ino %llu, new f_pos %#x", > + dbg_gen("feed '%s', ino %llu, new f_pos %#lx", > dent->name, (unsigned long long)le64_to_cpu(dent->inum), > - key_hash_flash(c, &dent->key)); > + (unsigned long)key_get_dir_pos(c, file, dent)); > ubifs_assert(le64_to_cpu(dent->ch.sqnum) > > ubifs_inode(dir)->creat_sqnum); > > @@ -656,7 +678,7 @@ static int ubifs_readdir(struct file *file, struct dir_context *ctx) > } > > kfree(file->private_data); > - ctx->pos = key_hash_flash(c, &dent->key); > + ctx->pos = key_get_dir_pos(c, file, dent); > file->private_data = dent; > cond_resched(); > } > diff --git a/fs/ubifs/key.h b/fs/ubifs/key.h > index 7547be512db2..2788e36ce832 100644 > --- a/fs/ubifs/key.h > +++ b/fs/ubifs/key.h > @@ -397,6 +397,65 @@ static inline uint32_t key_hash_flash(const struct ubifs_info *c, const void *k) > } > > /** > + * key_want_short_hash - tests whether we can emit a 64bit hash or not. > + * @file: the file handle of the directory > + */ > +static inline bool key_want_short_hash(struct file *file) > +{ > + if (file->f_mode & FMODE_32BITHASH) > + return true; > + > + if (!(file->f_mode & FMODE_64BITHASH) && is_32bit_api()) > + return true; > + > + return false; > +} > + > +/** > + * key_dir_pos - compute a 64bit directory cookie for readdir() > + * @c: UBIFS file-system description object > + * @file: the file handle of the directory > + * @dent: the directory entry > + */ > +static inline loff_t key_get_dir_pos(const struct ubifs_info *c, > + struct file *file, > + struct ubifs_dent_node *dent) > +{ > + BUILD_BUG_ON(sizeof(loff_t) < 8); > + > + if (key_want_short_hash(file)) > + return key_hash_flash(c, &dent->key); > + > + return ((loff_t)key_hash_flash(c, &dent->key)) << UBIFS_DH_BITS | le32_to_cpu(dent->cookie); > +} > + > +/** > + * key_get_hash_from_dir_pos - extracts the flash key from a directory offset. > + * @c: UBIFS file-system description object > + * @file: the file handle of the directory > + * @pos: the directory offset provied by VFS > + */ > +static inline uint32_t key_get_hash_from_dir_pos(const struct ubifs_info *c, > + struct file *file, loff_t pos) > +{ > + if (key_want_short_hash(file)) > + return pos & UBIFS_S_KEY_HASH_MASK; > + > + return (pos >> UBIFS_DH_BITS) & UBIFS_S_KEY_HASH_MASK; > +} > + > +/** > + * key_get_cookie_from_dir_pos - extracts the double hash cookie from a directory offset. > + * @c: UBIFS file-system description object > + * @pos: the directory offset provied by VFS > + */ > +static inline uint32_t key_get_cookie_from_dir_pos(const struct ubifs_info *c, > + loff_t pos) > +{ > + return pos & UBIFS_DH_MASK; > +} > + > +/** > * key_block - get data block number. > * @c: UBIFS file-system description object > * @key: the key to get the block number from > diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h > index 12f3df3ced0e..0532a6f82b1d 100644 > --- a/fs/ubifs/ubifs.h > +++ b/fs/ubifs/ubifs.h > @@ -40,6 +40,7 @@ > #include > #include > #include > +#include > #include "ubifs-media.h" > > /* Version of this UBIFS implementation */ > -- > 2.7.3 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html