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From:   Gabriel Krisman Bertazi <krisman@collabora.com>
To:     Arnaud Ferraris <arnaud.ferraris@collabora.com>
Cc:     linux-ext4@vger.kernel.org, drosen@google.com, ebiggers@kernel.org,
        tytso@mit.edu
Subject: Re: [PATCH RESEND v2 07/12] e2fsck: Support casefold directories
 when rehashing
Organization: Collabora
References: <20201210150353.91843-1-arnaud.ferraris@collabora.com>
        <20201210150353.91843-8-arnaud.ferraris@collabora.com>
Date:   Thu, 10 Dec 2020 17:53:57 -0300
In-Reply-To: <20201210150353.91843-8-arnaud.ferraris@collabora.com> (Arnaud
        Ferraris's message of "Thu, 10 Dec 2020 16:03:48 +0100")
Message-ID: <87y2i51ixm.fsf@collabora.com>
User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux)
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Precedence: bulk

Arnaud Ferraris <arnaud.ferraris@collabora.com> writes:

> From: Gabriel Krisman Bertazi <krisman@collabora.com>
>
> When rehashing a +F directory, the casefold comparison needs to be
> performed, in order to identify duplicated filenames.  Like the -F
> version, This is done in two steps, first adapt the qsort comparison to
> consider casefolded directories, and then iterate over the sorted list
> fixing dups.
>
> Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
> Signed-off-by: Arnaud Ferraris <arnaud.ferraris@collabora.com>
> ---
>  e2fsck/rehash.c | 88 ++++++++++++++++++++++++++++++++++++++++---------
>  1 file changed, 72 insertions(+), 16 deletions(-)
>
> diff --git a/e2fsck/rehash.c b/e2fsck/rehash.c
> index 30e510a6..14215011 100644
> --- a/e2fsck/rehash.c
> +++ b/e2fsck/rehash.c
> @@ -214,6 +214,23 @@ static EXT2_QSORT_TYPE ino_cmp(const void *a, const void *b)
>  	return (he_a->ino - he_b->ino);
>  }
>  
> +struct name_cmp_ctx
> +{
> +	int casefold;
> +	const struct ext2fs_nls_table *tbl;
> +};
> +
> +
> +static int same_name(const struct name_cmp_ctx *cmp_ctx, char *s1,
> +		     int len1, char *s2, int len2)
> +{
> +	if (!cmp_ctx->casefold)
> +		return (len1 == len2 &&	!memcmp(s1, s2, len1));
> +	else
> +		return !ext2fs_casefold_cmp(cmp_ctx->tbl,
> +					    s1, len1, s2, len2);
> +}
> +
>  /* Used for sorting the hash entry */
>  static EXT2_QSORT_TYPE name_cmp(const void *a, const void *b)
>  {
> @@ -240,9 +257,35 @@ static EXT2_QSORT_TYPE name_cmp(const void *a, const void *b)
>  	return ret;
>  }
>  
> +static EXT2_QSORT_TYPE name_cf_cmp(const struct name_cmp_ctx *ctx,
> +				   const void *a, const void *b)
> +{
> +	const struct hash_entry *he_a = (const struct hash_entry *) a;
> +	const struct hash_entry *he_b = (const struct hash_entry *) b;
> +	unsigned int he_a_len, he_b_len, min_len;
> +	int ret;
> +
> +	he_a_len = ext2fs_dirent_name_len(he_a->dir);
> +	he_b_len = ext2fs_dirent_name_len(he_b->dir);
> +
> +	ret = ext2fs_casefold_cmp(ctx->tbl, he_a->dir->name, he_a_len,
> +				  he_b->dir->name, he_b_len);
> +	if (ret == 0) {
> +		if (he_a_len > he_b_len)
> +			ret = 1;
> +		else if (he_a_len < he_b_len)
> +			ret = -1;
> +		else
> +			ret = he_b->dir->inode - he_a->dir->inode;
> +	}
> +	return ret;
> +}
> +
> +

extra line

>  /* Used for sorting the hash entry */
> -static EXT2_QSORT_TYPE hash_cmp(const void *a, const void *b)
> +static EXT2_QSORT_TYPE hash_cmp(const void *a, const void *b, void *arg)
>  {
> +	const struct name_cmp_ctx *ctx = (struct name_cmp_ctx *) arg;
>  	const struct hash_entry *he_a = (const struct hash_entry *) a;
>  	const struct hash_entry *he_b = (const struct hash_entry *) b;
>  	int	ret;
> @@ -256,8 +299,12 @@ static EXT2_QSORT_TYPE hash_cmp(const void *a, const void *b)
>  			ret = 1;
>  		else if (he_a->minor_hash < he_b->minor_hash)
>  			ret = -1;
> -		else
> -			ret = name_cmp(a, b);
> +		else {
> +			if (ctx->casefold)
> +				ret = name_cf_cmp(ctx, a, b);
> +			else
> +				ret = name_cmp(a, b);
> +		}
>  	}
>  	return ret;
>  }
> @@ -380,7 +427,8 @@ static void mutate_name(char *str, unsigned int *len)
>  
>  static int duplicate_search_and_fix(e2fsck_t ctx, ext2_filsys fs,
>  				    ext2_ino_t ino,
> -				    struct fill_dir_struct *fd)
> +				    struct fill_dir_struct *fd,
> +				    const struct name_cmp_ctx *cmp_ctx)
>  {
>  	struct problem_context	pctx;
>  	struct hash_entry	*ent, *prev;
> @@ -403,11 +451,12 @@ static int duplicate_search_and_fix(e2fsck_t ctx, ext2_filsys fs,
>  		ent = fd->harray + i;
>  		prev = ent - 1;
>  		if (!ent->dir->inode ||
> -		    (ext2fs_dirent_name_len(ent->dir) !=
> -		     ext2fs_dirent_name_len(prev->dir)) ||
> -		    memcmp(ent->dir->name, prev->dir->name,
> -			     ext2fs_dirent_name_len(ent->dir)))
> +		    !same_name(cmp_ctx, ent->dir->name,
> +			       ext2fs_dirent_name_len(ent->dir),
> +			       prev->dir->name,
> +			       ext2fs_dirent_name_len(prev->dir)))
>  			continue;
> +

noise.

Other than that, I think this is still good.

>  		pctx.dirent = ent->dir;
>  		if ((ent->dir->inode == prev->dir->inode) &&
>  		    fix_problem(ctx, PR_2_DUPLICATE_DIRENT, &pctx)) {
> @@ -426,10 +475,11 @@ static int duplicate_search_and_fix(e2fsck_t ctx, ext2_filsys fs,
>  		mutate_name(new_name, &new_len);
>  		for (j=0; j < fd->num_array; j++) {
>  			if ((i==j) ||
> -			    (new_len !=
> -			     (unsigned) ext2fs_dirent_name_len(fd->harray[j].dir)) ||
> -			    memcmp(new_name, fd->harray[j].dir->name, new_len))
> +			    !same_name(cmp_ctx, new_name, new_len,
> +				       fd->harray[j].dir->name,
> +				       ext2fs_dirent_name_len(fd->harray[j].dir))) {
>  				continue;
> +			}
>  			mutate_name(new_name, &new_len);
>  
>  			j = -1;
> @@ -894,6 +944,7 @@ errcode_t e2fsck_rehash_dir(e2fsck_t ctx, ext2_ino_t ino,
>  	struct fill_dir_struct	fd = { NULL, NULL, 0, 0, 0, NULL,
>  				       0, 0, 0, 0, 0, 0 };
>  	struct out_dir		outdir = { 0, 0, 0, 0 };
> +	struct name_cmp_ctx name_cmp_ctx = {0, NULL};
>  
>  	e2fsck_read_inode(ctx, ino, &inode, "rehash_dir");
>  
> @@ -921,6 +972,11 @@ errcode_t e2fsck_rehash_dir(e2fsck_t ctx, ext2_ino_t ino,
>  		fd.compress = 1;
>  	fd.parent = 0;
>  
> +	if (fs->encoding && (inode.i_flags & EXT4_CASEFOLD_FL)) {
> +		name_cmp_ctx.casefold = 1;
> +		name_cmp_ctx.tbl = fs->encoding;
> +	}
> +
>  retry_nohash:
>  	/* Read in the entire directory into memory */
>  	retval = ext2fs_block_iterate3(fs, ino, 0, 0,
> @@ -949,16 +1005,16 @@ retry_nohash:
>  	/* Sort the list */
>  resort:
>  	if (fd.compress && fd.num_array > 1)
> -		qsort(fd.harray+2, fd.num_array-2, sizeof(struct hash_entry),
> -		      hash_cmp);
> +		qsort_r(fd.harray+2, fd.num_array-2, sizeof(struct hash_entry),
> +			hash_cmp, &name_cmp_ctx);
>  	else
> -		qsort(fd.harray, fd.num_array, sizeof(struct hash_entry),
> -		      hash_cmp);
> +		qsort_r(fd.harray, fd.num_array, sizeof(struct hash_entry),
> +			hash_cmp, &name_cmp_ctx);
>  
>  	/*
>  	 * Look for duplicates
>  	 */
> -	if (duplicate_search_and_fix(ctx, fs, ino, &fd))
> +	if (duplicate_search_and_fix(ctx, fs, ino, &fd, &name_cmp_ctx))
>  		goto resort;
>  
>  	if (ctx->options & E2F_OPT_NO) {

-- 
Gabriel Krisman Bertazi