fat: fix data past EOF resulting from fsx testsuite (c0ef0cc9) · Commits · 戴 / test

When running FSX with direct I/O mode, fsx resulted in DATA past EOF issues. fsx ./file2 -Z -r 4096 -w 4096 ... .. truncating to largest ever: 0x907c fallocating to largest ever: 0x11137 truncating to largest ever: 0x2c6fe truncating to largest ever: 0x2cfdf fallocating to largest ever: 0x40000 Mapped Read: non-zero data past EOF (0x18628) page offset 0x629 is 0x2a4e ... .. The reason being, it is doing a truncate down, but the zeroing does not happen on the last block boundary when offset is not aligned. Even though it calls truncate_setsize()->truncate_inode_pages()-> truncate_inode_pages_range() and considers the partial zeroout but it retrieves the page using find_lock_page() - which only looks the page in the cache. So, zeroing out does not happen in case of direct IO. Make a truncate page based around block_truncate_page for FAT filesystem and invoke that helper to zerout in case the offset is not aligned with the blocksize. Signed-off-by:

Namjae Jeon <namjae.jeon@samsung.com> Signed-off-by:

Amit Sahrawat <a.sahrawat@samsung.com> Acked-by:

OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

fs/fat/fat.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -370,6 +370,7 @@ extern int fat_file_fsync(struct file *file, loff_t start, loff_t end,
		int datasync);

		/* fat/inode.c */
		extern int fat_block_truncate_page(struct inode *inode, loff_t from);
		extern void fat_attach(struct inode *inode, loff_t i_pos);
		extern void fat_detach(struct inode *inode);
		extern struct inode fat_iget(struct super_block sb, loff_t i_pos);

fs/fat/file.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -443,6 +443,9 @@ int fat_setattr(struct dentry dentry, struct iattr attr)
		}

		if (attr->ia_valid & ATTR_SIZE) {
		error = fat_block_truncate_page(inode, attr->ia_size);
		if (error)
		goto out;
		down_write(&MSDOS_I(inode)->truncate_lock);
		truncate_setsize(inode, attr->ia_size);
		fat_truncate_blocks(inode, attr->ia_size);

fs/fat/inode.c

+12 −0

Original line number	Diff line number	Diff line
		@@ -294,6 +294,18 @@ static sector_t _fat_bmap(struct address_space *mapping, sector_t block)
		return blocknr;
		}

		/*
		* fat_block_truncate_page() zeroes out a mapping from file offset `from'
		* up to the end of the block which corresponds to `from'.
		* This is required during truncate to physically zeroout the tail end
		* of that block so it doesn't yield old data if the file is later grown.
		* Also, avoid causing failure from fsx for cases of "data past EOF"
		*/
		int fat_block_truncate_page(struct inode *inode, loff_t from)
		{
		return block_truncate_page(inode->i_mapping, from, fat_get_block);
		}

		static const struct address_space_operations fat_aops = {
		.readpage = fat_readpage,
		.readpages = fat_readpages,

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