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Commit 6cda9fa2 authored by Ryusuke Konishi's avatar Ryusuke Konishi
Browse files

nilfs2: avoid rec_len overflow with 64KB block size 



With 64KB blocksize, a directory entry can have size 64KB which does
not fit into 16 bits we have for entry length.  So this patch stores
0xffff instead and converts value when read from / written to disk.

Nilfs derives its directory implementation from ext2 filesystem, and
this draws upon the corresponding change on ext2.

Signed-off-by: default avatarRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
parent c28e69d9

fs/nilfs2/dir.c

+14 −12
Original line number Diff line number Diff line
@@ -141,7 +141,7 @@ static void nilfs_check_page(struct page *page) 
	}

	for (offs = 0; offs <= limit - NILFS_DIR_REC_LEN(1); offs += rec_len) {

		p = (struct nilfs_dir_entry *)(kaddr + offs);

		rec_len = le16_to_cpu(p->rec_len);

		rec_len = nilfs_rec_len_from_disk(p->rec_len);



		if (rec_len < NILFS_DIR_REC_LEN(1))

			goto Eshort;
@@ -235,7 +235,8 @@ nilfs_match(int len, const unsigned char *name, struct nilfs_dir_entry *de) 
 */

static struct nilfs_dir_entry *nilfs_next_entry(struct nilfs_dir_entry *p)

{

	return (struct nilfs_dir_entry *)((char *)p + le16_to_cpu(p->rec_len));

	return (struct nilfs_dir_entry *)((char *)p +

					  nilfs_rec_len_from_disk(p->rec_len));

}



static unsigned char
@@ -326,7 +327,7 @@ static int nilfs_readdir(struct file *filp, void *dirent, filldir_t filldir) 
					goto success;

				}

			}

			filp->f_pos += le16_to_cpu(de->rec_len);

			filp->f_pos += nilfs_rec_len_from_disk(de->rec_len);

		}

		nilfs_put_page(page);

	}
@@ -441,7 +442,7 @@ void nilfs_set_link(struct inode *dir, struct nilfs_dir_entry *de, 
		    struct page *page, struct inode *inode)

{

	unsigned from = (char *) de - (char *) page_address(page);

	unsigned to = from + le16_to_cpu(de->rec_len);

	unsigned to = from + nilfs_rec_len_from_disk(de->rec_len);

	struct address_space *mapping = page->mapping;

	int err;
@@ -497,7 +498,7 @@ int nilfs_add_link(struct dentry *dentry, struct inode *inode) 
				/* We hit i_size */

				name_len = 0;

				rec_len = chunk_size;

				de->rec_len = cpu_to_le16(chunk_size);

				de->rec_len = nilfs_rec_len_to_disk(chunk_size);

				de->inode = 0;

				goto got_it;

			}
@@ -511,7 +512,7 @@ int nilfs_add_link(struct dentry *dentry, struct inode *inode) 
			if (nilfs_match(namelen, name, de))

				goto out_unlock;

			name_len = NILFS_DIR_REC_LEN(de->name_len);

			rec_len = le16_to_cpu(de->rec_len);

			rec_len = nilfs_rec_len_from_disk(de->rec_len);

			if (!de->inode && rec_len >= reclen)

				goto got_it;

			if (rec_len >= name_len + reclen)
@@ -534,8 +535,8 @@ got_it: 
		struct nilfs_dir_entry *de1;



		de1 = (struct nilfs_dir_entry *)((char *)de + name_len);

		de1->rec_len = cpu_to_le16(rec_len - name_len);

		de->rec_len = cpu_to_le16(name_len);

		de1->rec_len = nilfs_rec_len_to_disk(rec_len - name_len);

		de->rec_len = nilfs_rec_len_to_disk(name_len);

		de = de1;

	}

	de->name_len = namelen;
@@ -566,7 +567,8 @@ int nilfs_delete_entry(struct nilfs_dir_entry *dir, struct page *page) 
	struct inode *inode = mapping->host;

	char *kaddr = page_address(page);

	unsigned from = ((char *)dir - kaddr) & ~(nilfs_chunk_size(inode) - 1);

	unsigned to = ((char *)dir - kaddr) + le16_to_cpu(dir->rec_len);

	unsigned to = ((char *)dir - kaddr) +

		nilfs_rec_len_from_disk(dir->rec_len);

	struct nilfs_dir_entry *pde = NULL;

	struct nilfs_dir_entry *de = (struct nilfs_dir_entry *)(kaddr + from);

	int err;
@@ -587,7 +589,7 @@ int nilfs_delete_entry(struct nilfs_dir_entry *dir, struct page *page) 
	err = nilfs_prepare_chunk(page, mapping, from, to);

	BUG_ON(err);

	if (pde)

		pde->rec_len = cpu_to_le16(to - from);

		pde->rec_len = nilfs_rec_len_to_disk(to - from);

	dir->inode = 0;

	nilfs_commit_chunk(page, mapping, from, to);

	inode->i_ctime = inode->i_mtime = CURRENT_TIME;
@@ -621,14 +623,14 @@ int nilfs_make_empty(struct inode *inode, struct inode *parent) 
	memset(kaddr, 0, chunk_size);

	de = (struct nilfs_dir_entry *)kaddr;

	de->name_len = 1;

	de->rec_len = cpu_to_le16(NILFS_DIR_REC_LEN(1));

	de->rec_len = nilfs_rec_len_to_disk(NILFS_DIR_REC_LEN(1));

	memcpy(de->name, ".\0\0", 4);

	de->inode = cpu_to_le64(inode->i_ino);

	nilfs_set_de_type(de, inode);



	de = (struct nilfs_dir_entry *)(kaddr + NILFS_DIR_REC_LEN(1));

	de->name_len = 2;

	de->rec_len = cpu_to_le16(chunk_size - NILFS_DIR_REC_LEN(1));

	de->rec_len = nilfs_rec_len_to_disk(chunk_size - NILFS_DIR_REC_LEN(1));

	de->inode = cpu_to_le64(parent->i_ino);

	memcpy(de->name, "..\0", 4);

	nilfs_set_de_type(de, inode);

include/linux/nilfs2_fs.h

+18 −0
Original line number Diff line number Diff line
@@ -326,7 +326,25 @@ enum { 
#define NILFS_DIR_ROUND			(NILFS_DIR_PAD - 1)

#define NILFS_DIR_REC_LEN(name_len)	(((name_len) + 12 + NILFS_DIR_ROUND) & \

					~NILFS_DIR_ROUND)

#define NILFS_MAX_REC_LEN		((1<<16)-1)



static inline unsigned nilfs_rec_len_from_disk(__le16 dlen)

{

	unsigned len = le16_to_cpu(dlen);



	if (len == NILFS_MAX_REC_LEN)

		return 1 << 16;

	return len;

}



static inline __le16 nilfs_rec_len_to_disk(unsigned len)

{

	if (len == (1 << 16))

		return cpu_to_le16(NILFS_MAX_REC_LEN);

	else if (len > (1 << 16))

		BUG();

	return cpu_to_le16(len);

}



/**

 * struct nilfs_finfo - file information