Make the code handle the case of numlower > 1 and missing lowerdata
dentry gracefully.
Missing lowerdata dentry is an indication for lazy lookup of lowerdata
and in that case the lowerdata_redirect path is stored in ovl_inode.
Following commits will defer lookup and perform the lazy lookup on
access.
Reviewed-by: Alexander Larsson <alexl@xxxxxxxxxx>
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
fs/overlayfs/file.c | 7 +++++++
fs/overlayfs/inode.c | 18 ++++++++++++++----
fs/overlayfs/super.c | 11 +++++++++++
fs/overlayfs/util.c | 2 +-
4 files changed, 33 insertions(+), 5 deletions(-)
diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
index 7c04f033aadd..951683a66ff6 100644
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -115,6 +115,9 @@ static int ovl_real_fdget_meta(const struct file *file, struct fd *real,
ovl_path_real(dentry, &realpath);
else
ovl_path_realdata(dentry, &realpath);
+ /* TODO: lazy lookup of lowerdata */
+ if (!realpath.dentry)
+ return -EIO;
/* Has it been copied up since we'd opened it? */
if (unlikely(file_inode(real->file) != d_inode(realpath.dentry))) {
@@ -158,6 +161,10 @@ static int ovl_open(struct inode *inode, struct file *file)
file->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
ovl_path_realdata(dentry, &realpath);
+ /* TODO: lazy lookup of lowerdata */
+ if (!realpath.dentry)
+ return -EIO;
+
realfile = ovl_open_realfile(file, &realpath);
if (IS_ERR(realfile))
return PTR_ERR(realfile);
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index a7529b6a86e6..ebbe13bccc97 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -240,15 +240,22 @@ int ovl_getattr(struct mnt_idmap *idmap, const struct path *path,
/*
* If lower is not same as lowerdata or if there was
* no origin on upper, we can end up here.
+ * With lazy lowerdata lookup, guess lowerdata blocks
+ * from size to avoid lowerdata lookup on stat(2).
*/
struct kstat lowerdatastat;
u32 lowermask = STATX_BLOCKS;
ovl_path_lowerdata(dentry, &realpath);
- err = vfs_getattr(&realpath, &lowerdatastat,
- lowermask, flags);
- if (err)
- goto out;
+ if (realpath.dentry) {
+ err = vfs_getattr(&realpath, &lowerdatastat,
+ lowermask, flags);
+ if (err)
+ goto out;
+ } else {
+ lowerdatastat.blocks =
+ round_up(stat->size, stat->blksize) >> 9;
+ }
stat->blocks = lowerdatastat.blocks;
}
}
@@ -710,6 +717,9 @@ static int ovl_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
struct inode *realinode = ovl_inode_realdata(inode);
const struct cred *old_cred;
+ if (!realinode)
+ return -EIO;
+
if (!realinode->i_op->fiemap)
return -EOPNOTSUPP;
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index b960b9d84b66..ad9a68bec565 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -81,6 +81,14 @@ static struct dentry *ovl_d_real(struct dentry *dentry,
if (real && !inode && ovl_has_upperdata(d_inode(dentry)))
return real;
+ /*
+ * XXX: We may need lazy lookup of lowerdata for !inode case to return
+ * the real lowerdata dentry. The only current caller of d_real() with
+ * NULL inode is d_real_inode() from trace_uprobe and this caller is
+ * likely going to be followed reading from the file, before placing
+ * uprobes on offset within the file, so lowerdata should be available
+ * when setting the uprobe.
+ */
lower = ovl_dentry_lowerdata(dentry);
if (!lower)
goto bug;
@@ -103,6 +111,9 @@ static int ovl_revalidate_real(struct dentry *d, unsigned int flags, bool weak)
{
int ret = 1;
+ if (!d)
+ return 1;
+
if (weak) {
if (d->d_flags & DCACHE_OP_WEAK_REVALIDATE)
ret = d->d_op->d_weak_revalidate(d, flags);
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index ad93a3132495..9b7c0163734a 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -159,7 +159,7 @@ void ovl_dentry_init_flags(struct dentry *dentry, struct dentry *upperdentry,
if (upperdentry)
flags |= upperdentry->d_flags;
- for (i = 0; i < ovl_numlower(oe); i++)
+ for (i = 0; i < ovl_numlower(oe) && lowerstack[i].dentry; i++)
flags |= lowerstack[i].dentry->d_flags;
spin_lock(&dentry->d_lock);
--
2.34.1
