Try to use the new vfs rename flag RENAME_DT_UNKNOWN, to request
from underlying file system to mark copy up directory entries as
DT_UNKNOWN instead of their actual file type.
When copy ups are classified as DT_UNKNOWN, ovl_dir_read_merged() can
distinguish between copy up to opaque objects without having to check
the extended attribute trusted.overlay.inode on the iterated entries.
This will allow to know if upper d_inode value needs to be substitued
with lower d_inode value.
Because this is only done for optimization, it is not a problem
if file system does not respect the new RENAME_DT_UNKNOWN flag, which
is most likely the case, so we retry the rename without the flag.
This patch does not implement the actual optimization.
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
fs/overlayfs/copy_up.c | 8 +++++++-
fs/overlayfs/overlayfs.h | 5 +++++
2 files changed, 12 insertions(+), 1 deletion(-)
diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index f57043d..bcbcef5 100644
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -298,7 +298,13 @@ static int ovl_copy_up_locked(struct dentry *workdir, struct dentry *upperdir,
if (err)
goto out_cleanup;
- err = ovl_do_rename(wdir, newdentry, udir, upper, 0);
+ /*
+ * Mark copy up objects in upper as DT_UNKNOWN, so it easy to
+ * distinguish them from opaque objects in iterate_dir().
+ * File system repair tools may re-classify the file type
+ * and that will break optimization, but not functionality.
+ */
+ err = ovl_do_rename(wdir, newdentry, udir, upper, RENAME_DT_UNKNOWN);
if (err)
goto out_cleanup;
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 8af450b..54162c0 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -113,6 +113,11 @@ static inline int ovl_do_rename(struct inode *olddir, struct dentry *olddentry,
err = vfs_rename(olddir, olddentry, newdir, newdentry, NULL, flags);
+ /* retry without RENAME_VFS_DTYPE if fs does not support it */
+ if (err == -EINVAL && (flags & RENAME_VFS_DTYPE))
+ err = vfs_rename(olddir, olddentry, newdir, newdentry, NULL,
+ flags & RENAME_UAPI_MASK);
+
if (err) {
pr_debug("...rename(%pd2, %pd2, ...) = %i\n",
olddentry, newdentry, err);
--
2.7.4
--
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