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Commit d63b7090 authored by Evgeniy Dushistov's avatar Evgeniy Dushistov Committed by Linus Torvalds
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[PATCH] fix garbage instead of zeroes in UFS 



Looks like this is the problem, which point Al Viro some time ago:

ufs's get_block callback allocates 16k of disk at a time, and links that
entire 16k into the file's metadata.  But because get_block is called for only
a single buffer_head (a 2k buffer_head in this case?) we are only able to tell
the VFS that this 2k is buffer_new().

So when ufs_getfrag_block() is later called to map some more data in the file,
and when that data resides within the remaining 14k of this fragment,
ufs_getfrag_block() will incorrectly return a !buffer_new() buffer_head.

I don't see _right_ way to do nullification of whole block, if use inode
page cache, some pages may be outside of inode limits (inode size), and
will be lost; if use blockdev page cache it is possible to zero real data,
if later inode page cache will be used.

The simpliest way, as can I see usage of block device page cache, but not only
mark dirty, but also sync it during "nullification".  I use my simple tests
collection, which I used for check that create,open,write,read,close works on
ufs, and I see that this patch makes ufs code 18% slower then before.

Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 7ba34859

fs/ufs/balloc.c

+25 −0
Original line number Diff line number Diff line
@@ -275,6 +275,25 @@ static void ufs_change_blocknr(struct inode *inode, unsigned int baseblk, 
	UFSD("EXIT\n");

}



static void ufs_clear_frags(struct inode *inode, sector_t beg, unsigned int n,

			    int sync)

{

	struct buffer_head *bh;

	sector_t end = beg + n;



	for (; beg < end; ++beg) {

		bh = sb_getblk(inode->i_sb, beg);

		lock_buffer(bh);

		memset(bh->b_data, 0, inode->i_sb->s_blocksize);

		set_buffer_uptodate(bh);

		mark_buffer_dirty(bh);

		unlock_buffer(bh);

		if (IS_SYNC(inode) || sync)

			sync_dirty_buffer(bh);

		brelse(bh);

	}

}



unsigned ufs_new_fragments(struct inode * inode, __fs32 * p, unsigned fragment,

			   unsigned goal, unsigned count, int * err, struct page *locked_page)

{
@@ -350,6 +369,8 @@ unsigned ufs_new_fragments(struct inode * inode, __fs32 * p, unsigned fragment, 
			*p = cpu_to_fs32(sb, result);

			*err = 0;

			UFS_I(inode)->i_lastfrag = max_t(u32, UFS_I(inode)->i_lastfrag, fragment + count);

			ufs_clear_frags(inode, result + oldcount, newcount - oldcount,

					locked_page != NULL);

		}

		unlock_super(sb);

		UFSD("EXIT, result %u\n", result);
@@ -363,6 +384,8 @@ unsigned ufs_new_fragments(struct inode * inode, __fs32 * p, unsigned fragment, 
	if (result) {

		*err = 0;

		UFS_I(inode)->i_lastfrag = max_t(u32, UFS_I(inode)->i_lastfrag, fragment + count);

		ufs_clear_frags(inode, result + oldcount, newcount - oldcount,

				locked_page != NULL);

		unlock_super(sb);

		UFSD("EXIT, result %u\n", result);

		return result;
@@ -398,6 +421,8 @@ unsigned ufs_new_fragments(struct inode * inode, __fs32 * p, unsigned fragment, 
		*p = cpu_to_fs32(sb, result);

		*err = 0;

		UFS_I(inode)->i_lastfrag = max_t(u32, UFS_I(inode)->i_lastfrag, fragment + count);

		ufs_clear_frags(inode, result + oldcount, newcount - oldcount,

				locked_page != NULL);

		unlock_super(sb);

		if (newcount < request)

			ufs_free_fragments (inode, result + newcount, request - newcount);

fs/ufs/inode.c

+5 −36
Original line number Diff line number Diff line
@@ -156,36 +156,6 @@ out: 
	return ret;

}



static void ufs_clear_frag(struct inode *inode, struct buffer_head *bh)

{

	lock_buffer(bh);

	memset(bh->b_data, 0, inode->i_sb->s_blocksize);

	set_buffer_uptodate(bh);

	mark_buffer_dirty(bh);

	unlock_buffer(bh);

	if (IS_SYNC(inode))

		sync_dirty_buffer(bh);

}



static struct buffer_head *

ufs_clear_frags(struct inode *inode, sector_t beg,

		unsigned int n, sector_t want)

{

	struct buffer_head *res = NULL, *bh;

	sector_t end = beg + n;



	for (; beg < end; ++beg) {

		bh = sb_getblk(inode->i_sb, beg);

		ufs_clear_frag(inode, bh);

		if (want != beg)

			brelse(bh);

		else

			res = bh;

	}

	BUG_ON(!res);

	return res;

}



/**

 * ufs_inode_getfrag() - allocate new fragment(s)

 * @inode - pointer to inode
@@ -302,7 +272,7 @@ repeat: 
	}



	if (!phys) {

		result = ufs_clear_frags(inode, tmp, required, tmp + blockoff);

		result = sb_getblk(sb, tmp + blockoff);

	} else {

		*phys = tmp + blockoff;

		result = NULL;
@@ -403,8 +373,7 @@ repeat: 




	if (!phys) {

		result = ufs_clear_frags(inode, tmp, uspi->s_fpb,

					 tmp + blockoff);

		result = sb_getblk(sb, tmp + blockoff);

	} else {

		*phys = tmp + blockoff;

		*new = 1;
@@ -471,13 +440,13 @@ int ufs_getfrag_block(struct inode *inode, sector_t fragment, struct buffer_head 
#define GET_INODE_DATABLOCK(x) \

	ufs_inode_getfrag(inode, x, fragment, 1, &err, &phys, &new, bh_result->b_page)

#define GET_INODE_PTR(x) \

	ufs_inode_getfrag(inode, x, fragment, uspi->s_fpb, &err, NULL, NULL, bh_result->b_page)

	ufs_inode_getfrag(inode, x, fragment, uspi->s_fpb, &err, NULL, NULL, NULL)

#define GET_INDIRECT_DATABLOCK(x) \

	ufs_inode_getblock(inode, bh, x, fragment,	\

			  &err, &phys, &new, bh_result->b_page);

			  &err, &phys, &new, bh_result->b_page)

#define GET_INDIRECT_PTR(x) \

	ufs_inode_getblock(inode, bh, x, fragment,	\

			  &err, NULL, NULL, bh_result->b_page);

			  &err, NULL, NULL, NULL)



	if (ptr < UFS_NDIR_FRAGMENT) {

		bh = GET_INODE_DATABLOCK(ptr);