The patch below does not apply to the 3.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.
thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 5885ebda878b47c4b4602d4b0410cb4b282af024 Mon Sep 17 00:00:00 2001 From: Dave Chinner <[email protected]> Date: Mon, 23 Feb 2015 22:37:08 +1100 Subject: [PATCH] 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 <[email protected]> cc: <[email protected]> Signed-off-by: Dave Chinner <[email protected]> Reviewed-by: Brian Foster <[email protected]> Signed-off-by: Dave Chinner <[email protected]> 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; } diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h index 86cd6b39bed7..a1cd55f3f351 100644 --- a/fs/xfs/xfs_inode.h +++ b/fs/xfs/xfs_inode.h @@ -384,10 +384,11 @@ enum xfs_prealloc_flags { XFS_PREALLOC_INVISIBLE = (1 << 4), }; -int xfs_update_prealloc_flags(struct xfs_inode *, - enum xfs_prealloc_flags); -int xfs_zero_eof(struct xfs_inode *, xfs_off_t, xfs_fsize_t); -int xfs_iozero(struct xfs_inode *, loff_t, size_t); +int xfs_update_prealloc_flags(struct xfs_inode *ip, + enum xfs_prealloc_flags flags); +int xfs_zero_eof(struct xfs_inode *ip, xfs_off_t offset, + xfs_fsize_t isize, bool *did_zeroing); +int xfs_iozero(struct xfs_inode *ip, loff_t pos, size_t count); #define IHOLD(ip) \ diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c index d919ad7b16bf..e53a90331422 100644 --- a/fs/xfs/xfs_iops.c +++ b/fs/xfs/xfs_iops.c @@ -751,6 +751,7 @@ xfs_setattr_size( int error; uint lock_flags = 0; uint commit_flags = 0; + bool did_zeroing = false; trace_xfs_setattr(ip); @@ -794,20 +795,16 @@ xfs_setattr_size( return error; /* - * Now we can make the changes. Before we join the inode to the - * transaction, take care of the part of the truncation that must be - * done without the inode lock. This needs to be done before joining - * the inode to the transaction, because the inode cannot be unlocked - * once it is a part of the transaction. + * File data changes must be complete before we start the transaction to + * modify the inode. This needs to be done before joining the inode to + * the transaction because the inode cannot be unlocked once it is a + * part of the transaction. + * + * Start with zeroing any data block beyond EOF that we may expose on + * file extension. */ if (newsize > oldsize) { - /* - * Do the first part of growing a file: zero any data in the - * last block that is beyond the old EOF. We need to do this - * before the inode is joined to the transaction to modify - * i_size. - */ - error = xfs_zero_eof(ip, newsize, oldsize); + error = xfs_zero_eof(ip, newsize, oldsize, &did_zeroing); if (error) return error; } @@ -817,23 +814,18 @@ xfs_setattr_size( * any previous writes that are beyond the on disk EOF and the new * EOF that have not been written out need to be written here. If we * do not write the data out, we expose ourselves to the null files - * problem. - * - * Only flush from the on disk size to the smaller of the in memory - * file size or the new size as that's the range we really care about - * here and prevents waiting for other data not within the range we - * care about here. + * problem. Note that this includes any block zeroing we did above; + * otherwise those blocks may not be zeroed after a crash. */ - if (oldsize != ip->i_d.di_size && newsize > ip->i_d.di_size) { + if (newsize > ip->i_d.di_size && + (oldsize != ip->i_d.di_size || did_zeroing)) { error = filemap_write_and_wait_range(VFS_I(ip)->i_mapping, ip->i_d.di_size, newsize); if (error) return error; } - /* - * Wait for all direct I/O to complete. - */ + /* Now wait for all direct I/O to complete. */ inode_dio_wait(inode); /* -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
