[PATCH 04/12] xfs: handle unallocated inodes in xfs_inode_from_disk

Christoph Hellwig
2020-05-08T06:34:37Z

Handle inodes with a 0 di_mode in xfs_inode_from_disk, instead of partially
duplicating inode reading in xfs_iread.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
fs/xfs/libxfs/xfs_inode_buf.c | 50 ++++++++++-------------------------
1 file changed, 14 insertions(+), 36 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_inode_buf.c b/fs/xfs/libxfs/xfs_inode_buf.c
index abdecc80579e3..686a026b5f6ed 100644
--- a/fs/xfs/libxfs/xfs_inode_buf.c
+++ b/fs/xfs/libxfs/xfs_inode_buf.c
@@ -192,6 +192,17 @@ xfs_inode_from_disk(
ASSERT(ip->i_cowfp == NULL);
ASSERT(ip->i_afp == NULL);

+ /*
+ * First get the permanent information that is needed to allocate an
+ * inode. If the inode is unused, mode is zero and we shouldn't mess
+ * with the unitialized part of it.
+ */
+ to->di_flushiter = be16_to_cpu(from->di_flushiter);
+ inode->i_generation = be32_to_cpu(from->di_gen);
+ inode->i_mode = be16_to_cpu(from->di_mode);
+ if (!inode->i_mode)
+ return 0;
+
/*
* Convert v1 inodes immediately to v2 inode format as this is the
* minimum inode version format we support in the rest of the code.
@@ -209,7 +220,6 @@ xfs_inode_from_disk(
to->di_format = from->di_format;
i_uid_write(inode, be32_to_cpu(from->di_uid));
i_gid_write(inode, be32_to_cpu(from->di_gid));
- to->di_flushiter = be16_to_cpu(from->di_flushiter);

/*
* Time is signed, so need to convert to signed 32 bit before
@@ -223,8 +233,6 @@ xfs_inode_from_disk(
inode->i_mtime.tv_nsec = (int)be32_to_cpu(from->di_mtime.t_nsec);
inode->i_ctime.tv_sec = (int)be32_to_cpu(from->di_ctime.t_sec);
inode->i_ctime.tv_nsec = (int)be32_to_cpu(from->di_ctime.t_nsec);
- inode->i_generation = be32_to_cpu(from->di_gen);
- inode->i_mode = be16_to_cpu(from->di_mode);

to->di_size = be64_to_cpu(from->di_size);
to->di_nblocks = be64_to_cpu(from->di_nblocks);
@@ -653,39 +661,9 @@ xfs_iread(
goto out_brelse;
}

- /*
- * If the on-disk inode is already linked to a directory
- * entry, copy all of the inode into the in-core inode.
- * xfs_iformat_fork() handles copying in the inode format
- * specific information.
- * Otherwise, just get the truly permanent information.
- */
- if (dip->di_mode) {
- error = xfs_inode_from_disk(ip, dip);
- if (error) {
-#ifdef DEBUG
- xfs_alert(mp, "%s: xfs_iformat() returned error %d",
- __func__, error);
-#endif /* DEBUG */
- goto out_brelse;
- }
- } else {
- /*
- * Partial initialisation of the in-core inode. Just the bits
- * that xfs_ialloc won't overwrite or relies on being correct.
- */
- VFS_I(ip)->i_generation = be32_to_cpu(dip->di_gen);
- ip->i_d.di_flushiter = be16_to_cpu(dip->di_flushiter);
-
- /*
- * Make sure to pull in the mode here as well in
- * case the inode is released without being used.
- * This ensures that xfs_inactive() will see that
- * the inode is already free and not try to mess
- * with the uninitialized part of it.
- */
- VFS_I(ip)->i_mode = 0;
- }
+ error = xfs_inode_from_disk(ip, dip);
+ if (error)
+ goto out_brelse;

ip->i_delayed_blks = 0;

--
2.26.2