[PATCH v2] fs: clear writeback errors in inode_init_always

Darrick J. Wong
2018-05-22T04:06:51Z

From: Darrick J. Wong <darrick.wong@oracle.com>

In inode_init_always(), we clear the inode mapping flags, which clears
any retained error (AS_EIO, AS_ENOSPC) bits. Unfortunately, we do not
also clear wb_err, which means that old mapping errors can leak through
to new inodes.

This is crucial for the XFS inode allocation path because we recycle old
in-core inodes and we do not want error state from an old file to leak
into the new file. This bug was discovered by running generic/036 and
generic/047 in a loop and noticing that the EIOs generated by the
collision of direct and buffered writes in generic/036 would survive the
remount between 036 and 047, and get reported to the fsyncs (on
different files!) in generic/047.

Since we're changing the semantics of inode_init_always, we must also
change xfs_reinit_inode to retain the writeback error state when we go
to recover an inode that has been torn down in the vfs but not yet
disposed of by XFS.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
v2: retain AS_EIO/AS_ENOSPC across xfs inode reinit
---
fs/inode.c | 1 +
fs/xfs/xfs_icache.c | 9 +++++++++
2 files changed, 10 insertions(+)

diff --git a/fs/inode.c b/fs/inode.c
index 13ceb98c3bd3..3b55391072f3 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -178,6 +178,7 @@ int inode_init_always(struct super_block *sb, struct inode *inode)
mapping->a_ops = &empty_aops;
mapping->host = inode;
mapping->flags = 0;
+ mapping->wb_err = 0;
atomic_set(&mapping->i_mmap_writable, 0);
mapping_set_gfp_mask(mapping, GFP_HIGHUSER_MOVABLE);
mapping->private_data = NULL;
diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
index 164350d91efc..d01f9544ff01 100644
--- a/fs/xfs/xfs_icache.c
+++ b/fs/xfs/xfs_icache.c
@@ -298,6 +298,10 @@ xfs_reinit_inode(
uint64_t version = inode_peek_iversion(inode);
umode_t mode = inode->i_mode;
dev_t dev = inode->i_rdev;
+ errseq_t old_err = inode->i_mapping->wb_err;
+ bool as_eio = test_bit(AS_EIO, &inode->i_mapping->flags);
+ bool as_enospc = test_bit(AS_ENOSPC,
+ &inode->i_mapping->flags);

error = inode_init_always(mp->m_super, inode);

@@ -306,6 +310,11 @@ xfs_reinit_inode(
inode_set_iversion_queried(inode, version);
inode->i_mode = mode;
inode->i_rdev = dev;
+ inode->i_mapping->wb_err = old_err;
+ if (as_eio)
+ set_bit(AS_EIO, &inode->i_mapping->flags);
+ if (as_enospc)
+ set_bit(AS_ENOSPC, &inode->i_mapping->flags);
return error;
}