Commit 2b5379f7 authored by Gao Xiang's avatar Gao Xiang
Browse files

erofs: use meta buffers for super operations 

Get rid of old erofs_get_meta_page() within super operations by
using on-stack meta buffers in order to prepare subpage and folio
features.

Link: https://lore.kernel.org/r/20220102081317.109797-1-hsiangkao@linux.alibaba.com


Reviewed-by: default avatarYue Hu <huyue2@yulong.com>
Reviewed-by: default avatarLiu Bo <bo.liu@linux.alibaba.com>
Reviewed-by: default avatarChao Yu <chao@kernel.org>
Signed-off-by: default avatarGao Xiang <hsiangkao@linux.alibaba.com>
parent c521e3ad

fs/erofs/super.c

+27 −77
Original line number Diff line number Diff line
@@ -2,6 +2,7 @@ 
/*

 * Copyright (C) 2017-2018 HUAWEI, Inc.

 *             https://www.huawei.com/

 * Copyright (C) 2021, Alibaba Cloud

 */

#include <linux/module.h>

#include <linux/buffer_head.h>
@@ -124,80 +125,50 @@ static bool check_layout_compatibility(struct super_block *sb, 


#ifdef CONFIG_EROFS_FS_ZIP

/* read variable-sized metadata, offset will be aligned by 4-byte */

static void *erofs_read_metadata(struct super_block *sb, struct page **pagep,

static void *erofs_read_metadata(struct super_block *sb, struct erofs_buf *buf,

				 erofs_off_t *offset, int *lengthp)

{

	struct page *page = *pagep;

	u8 *buffer, *ptr;

	int len, i, cnt;

	erofs_blk_t blk;



	*offset = round_up(*offset, 4);

	blk = erofs_blknr(*offset);

	ptr = erofs_read_metabuf(buf, sb, erofs_blknr(*offset), EROFS_KMAP);

	if (IS_ERR(ptr))

		return ptr;



	if (!page || page->index != blk) {

		if (page) {

			unlock_page(page);

			put_page(page);

		}

		page = erofs_get_meta_page(sb, blk);

		if (IS_ERR(page))

			goto err_nullpage;

	}



	ptr = kmap(page);

	len = le16_to_cpu(*(__le16 *)&ptr[erofs_blkoff(*offset)]);

	if (!len)

		len = U16_MAX + 1;

	buffer = kmalloc(len, GFP_KERNEL);

	if (!buffer) {

		buffer = ERR_PTR(-ENOMEM);

		goto out;

	}

	if (!buffer)

		return ERR_PTR(-ENOMEM);

	*offset += sizeof(__le16);

	*lengthp = len;



	for (i = 0; i < len; i += cnt) {

		cnt = min(EROFS_BLKSIZ - (int)erofs_blkoff(*offset), len - i);

		blk = erofs_blknr(*offset);



		if (!page || page->index != blk) {

			if (page) {

				kunmap(page);

				unlock_page(page);

				put_page(page);

			}

			page = erofs_get_meta_page(sb, blk);

			if (IS_ERR(page)) {

		ptr = erofs_read_metabuf(buf, sb, erofs_blknr(*offset),

					 EROFS_KMAP);

		if (IS_ERR(ptr)) {

			kfree(buffer);

				goto err_nullpage;

			}

			ptr = kmap(page);

			return ptr;

		}

		memcpy(buffer + i, ptr + erofs_blkoff(*offset), cnt);

		*offset += cnt;

	}

out:

	kunmap(page);

	*pagep = page;

	return buffer;

err_nullpage:

	*pagep = NULL;

	return page;

}



static int erofs_load_compr_cfgs(struct super_block *sb,

				 struct erofs_super_block *dsb)

{

	struct erofs_sb_info *sbi;

	struct page *page;

	struct erofs_sb_info *sbi = EROFS_SB(sb);

	struct erofs_buf buf = __EROFS_BUF_INITIALIZER;

	unsigned int algs, alg;

	erofs_off_t offset;

	int size, ret;

	int size, ret = 0;



	sbi = EROFS_SB(sb);

	sbi->available_compr_algs = le16_to_cpu(dsb->u1.available_compr_algs);



	if (sbi->available_compr_algs & ~Z_EROFS_ALL_COMPR_ALGS) {

		erofs_err(sb, "try to load compressed fs with unsupported algorithms %x",

			  sbi->available_compr_algs & ~Z_EROFS_ALL_COMPR_ALGS);
@@ -205,20 +176,17 @@ static int erofs_load_compr_cfgs(struct super_block *sb, 
	}



	offset = EROFS_SUPER_OFFSET + sbi->sb_size;

	page = NULL;

	alg = 0;

	ret = 0;



	for (algs = sbi->available_compr_algs; algs; algs >>= 1, ++alg) {

		void *data;



		if (!(algs & 1))

			continue;



		data = erofs_read_metadata(sb, &page, &offset, &size);

		data = erofs_read_metadata(sb, &buf, &offset, &size);

		if (IS_ERR(data)) {

			ret = PTR_ERR(data);

			goto err;

			break;

		}



		switch (alg) {
@@ -234,13 +202,9 @@ static int erofs_load_compr_cfgs(struct super_block *sb, 
		}

		kfree(data);

		if (ret)

			goto err;

	}

err:

	if (page) {

		unlock_page(page);

		put_page(page);

			break;

	}

	erofs_put_metabuf(&buf);

	return ret;

}

#else
@@ -261,7 +225,7 @@ static int erofs_init_devices(struct super_block *sb, 
	struct erofs_sb_info *sbi = EROFS_SB(sb);

	unsigned int ondisk_extradevs;

	erofs_off_t pos;

	struct page *page = NULL;

	struct erofs_buf buf = __EROFS_BUF_INITIALIZER;

	struct erofs_device_info *dif;

	struct erofs_deviceslot *dis;

	void *ptr;
@@ -285,22 +249,13 @@ static int erofs_init_devices(struct super_block *sb, 
	pos = le16_to_cpu(dsb->devt_slotoff) * EROFS_DEVT_SLOT_SIZE;

	down_read(&sbi->devs->rwsem);

	idr_for_each_entry(&sbi->devs->tree, dif, id) {

		erofs_blk_t blk = erofs_blknr(pos);

		struct block_device *bdev;



		if (!page || page->index != blk) {

			if (page) {

				kunmap(page);

				unlock_page(page);

				put_page(page);

			}



			page = erofs_get_meta_page(sb, blk);

			if (IS_ERR(page)) {

				up_read(&sbi->devs->rwsem);

				return PTR_ERR(page);

			}

			ptr = kmap(page);

		ptr = erofs_read_metabuf(&buf, sb, erofs_blknr(pos),

					 EROFS_KMAP);

		if (IS_ERR(ptr)) {

			err = PTR_ERR(ptr);

			break;

		}

		dis = ptr + erofs_blkoff(pos);
@@ -309,7 +264,7 @@ static int erofs_init_devices(struct super_block *sb, 
					  sb->s_type);

		if (IS_ERR(bdev)) {

			err = PTR_ERR(bdev);

			goto err_out;

			break;

		}

		dif->bdev = bdev;

		dif->dax_dev = fs_dax_get_by_bdev(bdev);
@@ -318,13 +273,8 @@ static int erofs_init_devices(struct super_block *sb, 
		sbi->total_blocks += dif->blocks;

		pos += EROFS_DEVT_SLOT_SIZE;

	}

err_out:

	up_read(&sbi->devs->rwsem);

	if (page) {

		kunmap(page);

		unlock_page(page);

		put_page(page);

	}

	erofs_put_metabuf(&buf);

	return err;

}