xfs: set inode sick state flags when we zap either ondisk fork

In a few patches, we'll add some online repair code that tries to
massage the ondisk inode record just enough to get it to pass the inode
verifiers so that we can continue with more file repairs.  Part of that
massaging can include zapping the ondisk forks to clear errors.  After
that point, the bmap fork repair functions will rebuild the zapped
forks.

Christoph asked for stronger protections against online repair zapping a
fork to get the inode to load vs. other threads trying to access the
partially repaired file.  Do this by adding a special "[DA]FORK_ZAPPED"
inode health flag whenever repair zaps a fork, and sprinkling checks for
that flag into the various file operations for things that don't like
handling an unexpected zero-extents fork.

In practice xfs_scrub will scrub and fix the forks almost immediately
after zapping them, so the window is very small.  However, if a crash or
unmount should occur, we can still detect these zapped inode forks by
looking for a zero-extents fork when data was expected.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

1 files changed, 35 insertions, 0 deletions

diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index c0f1c89786c2..ea6b277485a4 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -37,6 +37,7 @@
 #include "xfs_reflink.h"
 #include "xfs_ag.h"
 #include "xfs_log_priv.h"
+#include "xfs_health.h"
 
 struct kmem_cache *xfs_inode_cache;
 
@@ -661,6 +662,8 @@ xfs_lookup(
 
 	if (xfs_is_shutdown(dp->i_mount))
 		return -EIO;
+	if (xfs_ifork_zapped(dp, XFS_DATA_FORK))
+		return -EIO;
 
 	error = xfs_dir_lookup(NULL, dp, name, &inum, ci_name);
 	if (error)
@@ -978,6 +981,8 @@ xfs_create(
 
 	if (xfs_is_shutdown(mp))
 		return -EIO;
+	if (xfs_ifork_zapped(dp, XFS_DATA_FORK))
+		return -EIO;
 
 	prid = xfs_get_initial_prid(dp);
 
@@ -1217,6 +1222,8 @@ xfs_link(
 
 	if (xfs_is_shutdown(mp))
 		return -EIO;
+	if (xfs_ifork_zapped(tdp, XFS_DATA_FORK))
+		return -EIO;
 
 	error = xfs_qm_dqattach(sip);
 	if (error)
@@ -2506,6 +2513,8 @@ xfs_remove(
 
 	if (xfs_is_shutdown(mp))
 		return -EIO;
+	if (xfs_ifork_zapped(dp, XFS_DATA_FORK))
+		return -EIO;
 
 	error = xfs_qm_dqattach(dp);
 	if (error)
@@ -3758,3 +3767,29 @@ xfs_inode_reload_unlinked(
 
 	return error;
 }
+
+/* Has this inode fork been zapped by repair? */
+bool
+xfs_ifork_zapped(
+	const struct xfs_inode	*ip,
+	int			whichfork)
+{
+	unsigned int		datamask = 0;
+
+	switch (whichfork) {
+	case XFS_DATA_FORK:
+		switch (ip->i_vnode.i_mode & S_IFMT) {
+		case S_IFDIR:
+			datamask = XFS_SICK_INO_DIR_ZAPPED;
+			break;
+		case S_IFLNK:
+			datamask = XFS_SICK_INO_SYMLINK_ZAPPED;
+			break;
+		}
+		return ip->i_sick & (XFS_SICK_INO_BMBTD_ZAPPED | datamask);
+	case XFS_ATTR_FORK:
+		return ip->i_sick & XFS_SICK_INO_BMBTA_ZAPPED;
+	default:
+		return false;
+	}
+}