From 5885ebda878b47c4b4602d4b0410cb4b282af024 Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Mon, 23 Feb 2015 22:37:08 +1100 Subject: xfs: ensure truncate forces zeroed blocks to disk A new fsync vs power fail test in xfstests indicated that XFS can have unreliable data consistency when doing extending truncates that require block zeroing. The blocks beyond EOF get zeroed in memory, but we never force those changes to disk before we run the transaction that extends the file size and exposes those blocks to userspace. This can result in the blocks not being correctly zeroed after a crash. Because in-memory behaviour is correct, tools like fsx don't pick up any coherency problems - it's not until the filesystem is shutdown or the system crashes after writing the truncate transaction to the journal but before the zeroed data in the page cache is flushed that the issue is exposed. Fix this by also flushing the dirty data in memory region between the old size and new size when we've found blocks that need zeroing in the truncate process. Reported-by: Liu Bo cc: Signed-off-by: Dave Chinner Reviewed-by: Brian Foster Signed-off-by: Dave Chinner --- fs/xfs/xfs_file.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) (limited to 'fs/xfs/xfs_file.c') diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index ce615d12fb44..a2e1cb8a568b 100644 --- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c @@ -397,7 +397,8 @@ STATIC int /* error (positive) */ xfs_zero_last_block( struct xfs_inode *ip, xfs_fsize_t offset, - xfs_fsize_t isize) + xfs_fsize_t isize, + bool *did_zeroing) { struct xfs_mount *mp = ip->i_mount; xfs_fileoff_t last_fsb = XFS_B_TO_FSBT(mp, isize); @@ -425,6 +426,7 @@ xfs_zero_last_block( zero_len = mp->m_sb.sb_blocksize - zero_offset; if (isize + zero_len > offset) zero_len = offset - isize; + *did_zeroing = true; return xfs_iozero(ip, isize, zero_len); } @@ -443,7 +445,8 @@ int /* error (positive) */ xfs_zero_eof( struct xfs_inode *ip, xfs_off_t offset, /* starting I/O offset */ - xfs_fsize_t isize) /* current inode size */ + xfs_fsize_t isize, /* current inode size */ + bool *did_zeroing) { struct xfs_mount *mp = ip->i_mount; xfs_fileoff_t start_zero_fsb; @@ -465,7 +468,7 @@ xfs_zero_eof( * We only zero a part of that block so it is handled specially. */ if (XFS_B_FSB_OFFSET(mp, isize) != 0) { - error = xfs_zero_last_block(ip, offset, isize); + error = xfs_zero_last_block(ip, offset, isize, did_zeroing); if (error) return error; } @@ -525,6 +528,7 @@ xfs_zero_eof( if (error) return error; + *did_zeroing = true; start_zero_fsb = imap.br_startoff + imap.br_blockcount; ASSERT(start_zero_fsb <= (end_zero_fsb + 1)); } @@ -567,13 +571,15 @@ restart: * having to redo all checks before. */ if (*pos > i_size_read(inode)) { + bool zero = false; + if (*iolock == XFS_IOLOCK_SHARED) { xfs_rw_iunlock(ip, *iolock); *iolock = XFS_IOLOCK_EXCL; xfs_rw_ilock(ip, *iolock); goto restart; } - error = xfs_zero_eof(ip, *pos, i_size_read(inode)); + error = xfs_zero_eof(ip, *pos, i_size_read(inode), &zero); if (error) return error; } -- cgit v1.2.3