From d63b70902befe189ba2672925f28ec3f4db41352 Mon Sep 17 00:00:00 2001 From: Evgeniy Dushistov Date: Fri, 5 Jan 2007 16:37:04 -0800 Subject: [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: Andrew Morton Signed-off-by: Linus Torvalds --- fs/ufs/balloc.c | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) (limited to 'fs/ufs/balloc.c') diff --git a/fs/ufs/balloc.c b/fs/ufs/balloc.c index b82381475779..2e0021e8f366 100644 --- a/fs/ufs/balloc.c +++ b/fs/ufs/balloc.c @@ -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); -- cgit v1.2.3