Re: [PATCH v2 3/5] erofs: use meta buffers for super operations

[Gao Xiang]

Hi Bo,

On Sun, Jan 02, 2022 at 03:23:21PM +0800, Liu Bo wrote:
> On Sun, Jan 02, 2022 at 12:00:15PM +0800, Gao Xiang wrote:

...

> > -			ptr = kmap(page);
> > -		}
> > +		ptr = erofs_read_metabuf(buf, sb, erofs_blknr(*offset),
> > +					 EROFS_KMAP);
> > +		if (IS_ERR(ptr))
> 
> kfree(buffer) is missing.
> 
> > +			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);
> > @@ -205,21 +174,16 @@ 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);
> > -		if (IS_ERR(data)) {
> > -			ret = PTR_ERR(data);
> > -			goto err;
> > -		}
> > +		data = erofs_read_metadata(sb, &buf, &offset, &size);
> 
> if PTR_ERR(data) is -ENOMEM, buf needs to be put according to the
> current design.
> 
> > +		if (IS_ERR(data))
> > +			return PTR_ERR(data);
> >  
> >  		switch (alg) {
> >  		case Z_EROFS_COMPRESSION_LZ4:
> > @@ -234,13 +198,9 @@ 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 +221,7 @@ 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 +245,13 @@ 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)) {
> 
> Ditto.
> 

Thanks for catching these! I've fixed these as follows,
please help check out again!

Thanks,
Gao Xiang

diff --git a/fs/erofs/super.c b/fs/erofs/super.c
index 38305fa2969b..9e076303bb24 100644
--- a/fs/erofs/super.c
+++ b/fs/erofs/super.c
@@ -149,8 +149,10 @@ static void *erofs_read_metadata(struct super_block *sb, struct erofs_buf *buf,
 		cnt = min(EROFS_BLKSIZ - (int)erofs_blkoff(*offset), len - i);
 		ptr = erofs_read_metabuf(buf, sb, erofs_blknr(*offset),
 					 EROFS_KMAP);
-		if (IS_ERR(ptr))
+		if (IS_ERR(ptr)) {
+			kfree(buffer);
 			return ptr;
+		}
 		memcpy(buffer + i, ptr + erofs_blkoff(*offset), cnt);
 		*offset += cnt;
 	}
@@ -182,8 +184,10 @@ static int erofs_load_compr_cfgs(struct super_block *sb,
 			continue;
 
 		data = erofs_read_metadata(sb, &buf, &offset, &size);
-		if (IS_ERR(data))
-			return PTR_ERR(data);
+		if (IS_ERR(data)) {
+			ret = PTR_ERR(data);
+			break;
+		}
 
 		switch (alg) {
 		case Z_EROFS_COMPRESSION_LZ4:
@@ -250,8 +254,8 @@ static int erofs_init_devices(struct super_block *sb,
 		ptr = erofs_read_metabuf(&buf, sb, erofs_blknr(pos),
 					 EROFS_KMAP);
 		if (IS_ERR(ptr)) {
-			up_read(&sbi->devs->rwsem);
-			return PTR_ERR(ptr);
+			err = PTR_ERR(ptr);
+			break;
 		}
 		dis = ptr + erofs_blkoff(pos);
 
@@ -260,7 +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);