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Commit ebab8990 authored by Anton Altaparmakov's avatar Anton Altaparmakov Committed by Linus Torvalds
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NTFS: Fix read regression. 



The regression was caused by:
        commit[a32ea1e1] Fix read/truncate race

This causes ntfs_readpage() to be called for a zero i_size inode, which
failed when the file was compressed and non-resident.

Thanks a lot to Mike Galbraith for reporting the issue and tracking down
the commit that caused the regression.

Looking into it I found three bugs which the patch fixes.

Signed-off-by: default avatarAnton Altaparmakov <aia21@cantab.net>
Tested-by: default avatarMike Galbraith <efault@gmx.de>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 74521c28

fs/ntfs/aops.c

+9 −1
Original line number Diff line number Diff line
@@ -405,6 +405,15 @@ static int ntfs_readpage(struct file *file, struct page *page) 


retry_readpage:

	BUG_ON(!PageLocked(page));

	vi = page->mapping->host;

	i_size = i_size_read(vi);

	/* Is the page fully outside i_size? (truncate in progress) */

	if (unlikely(page->index >= (i_size + PAGE_CACHE_SIZE - 1) >>

			PAGE_CACHE_SHIFT)) {

		zero_user_page(page, 0, PAGE_CACHE_SIZE, KM_USER0);

		ntfs_debug("Read outside i_size - truncated?");

		goto done;

	}

	/*

	 * This can potentially happen because we clear PageUptodate() during

	 * ntfs_writepage() of MstProtected() attributes.
@@ -413,7 +422,6 @@ retry_readpage: 
		unlock_page(page);

		return 0;

	}

	vi = page->mapping->host;

	ni = NTFS_I(vi);

	/*

	 * Only $DATA attributes can be encrypted and only unnamed $DATA

fs/ntfs/attrib.c

+1 −4
Original line number Diff line number Diff line
@@ -179,10 +179,7 @@ int ntfs_map_runlist_nolock(ntfs_inode *ni, VCN vcn, ntfs_attr_search_ctx *ctx) 
	 * ntfs_mapping_pairs_decompress() fails.

	 */

	end_vcn = sle64_to_cpu(a->data.non_resident.highest_vcn) + 1;

	if (!a->data.non_resident.lowest_vcn && end_vcn == 1)

		end_vcn = sle64_to_cpu(a->data.non_resident.allocated_size) >>

				ni->vol->cluster_size_bits;

	if (unlikely(vcn >= end_vcn)) {

	if (unlikely(vcn && vcn >= end_vcn)) {

		err = -ENOENT;

		goto err_out;

	}

fs/ntfs/compress.c

+10 −0
Original line number Diff line number Diff line
@@ -561,6 +561,16 @@ int ntfs_read_compressed_block(struct page *page) 
	read_unlock_irqrestore(&ni->size_lock, flags);

	max_page = ((i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT) -

			offset;

	/* Is the page fully outside i_size? (truncate in progress) */

	if (xpage >= max_page) {

		kfree(bhs);

		kfree(pages);

		zero_user_page(page, 0, PAGE_CACHE_SIZE, KM_USER0);

		ntfs_debug("Compressed read outside i_size - truncated?");

		SetPageUptodate(page);

		unlock_page(page);

		return 0;

	}

	if (nr_pages < max_page)

		max_page = nr_pages;

	for (i = 0; i < max_page; i++, offset++) {