When overlay layers are not all on the same fs, but all inode numbers
of underlying fs do not use the high 'xino' bits, overlay st_ino values
are constant and persistent.
In that case, relax non-samefs constraint for consistent d_ino and always
iterate non-merge dir using ovl_fill_real() actor so we can remap lower
inode numbers to unique lower fs range.
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
fs/overlayfs/readdir.c | 45 +++++++++++++++++++++++++++++++++++++++------
1 file changed, 39 insertions(+), 6 deletions(-)
diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c
index c11f5c0906c3..ef1fe42ff7bb 100644
--- a/fs/overlayfs/readdir.c
+++ b/fs/overlayfs/readdir.c
@@ -120,6 +120,10 @@ static bool ovl_calc_d_ino(struct ovl_readdir_data *rdd,
if (!rdd->dentry)
return false;
+ /* Always recalc d_ino when remapping lower inode numbers */
+ if (ovl_xino_bits(rdd->dentry->d_sb))
+ return true;
+
/* Always recalc d_ino for parent */
if (strcmp(p->name, "..") == 0)
return true;
@@ -435,6 +439,19 @@ static struct ovl_dir_cache *ovl_cache_get(struct dentry *dentry)
return cache;
}
+/* Map inode number to lower fs unique range */
+static u64 ovl_remap_lower_ino(u64 ino, int xinobits, int fsid,
+ const char *name, int namelen)
+{
+ if (ino >> (64 - xinobits)) {
+ pr_warn_ratelimited("overlayfs: d_ino too big (%.*s, ino=%llu, xinobits=%d)\n",
+ namelen, name, ino, xinobits);
+ return ino;
+ }
+
+ return ino | ((u64)fsid) << (64 - xinobits);
+}
+
/*
* Set d_ino for upper entries. Non-upper entries should always report
* the uppermost real inode ino and should not call this function.
@@ -452,9 +469,10 @@ static int ovl_cache_update_ino(struct path *path, struct ovl_cache_entry *p)
struct dentry *this = NULL;
enum ovl_path_type type;
u64 ino = p->real_ino;
+ int xinobits = ovl_xino_bits(dir->d_sb);
int err = 0;
- if (!ovl_same_sb(dir->d_sb))
+ if (!ovl_same_sb(dir->d_sb) && !xinobits)
goto out;
if (p->name[0] == '.') {
@@ -491,6 +509,10 @@ static int ovl_cache_update_ino(struct path *path, struct ovl_cache_entry *p)
WARN_ON_ONCE(dir->d_sb->s_dev != stat.dev);
ino = stat.ino;
+ } else if (xinobits && !OVL_TYPE_UPPER(type)) {
+ ino = ovl_remap_lower_ino(ino, xinobits,
+ ovl_layer_lower(this)->fsid,
+ p->name, p->len);
}
out:
@@ -618,6 +640,8 @@ struct ovl_readdir_translate {
struct ovl_dir_cache *cache;
struct dir_context ctx;
u64 parent_ino;
+ int fsid;
+ int xinobits;
};
static int ovl_fill_real(struct dir_context *ctx, const char *name,
@@ -628,14 +652,17 @@ static int ovl_fill_real(struct dir_context *ctx, const char *name,
container_of(ctx, struct ovl_readdir_translate, ctx);
struct dir_context *orig_ctx = rdt->orig_ctx;
- if (rdt->parent_ino && strcmp(name, "..") == 0)
+ if (rdt->parent_ino && strcmp(name, "..") == 0) {
ino = rdt->parent_ino;
- else if (rdt->cache) {
+ } else if (rdt->cache) {
struct ovl_cache_entry *p;
p = ovl_cache_entry_find(&rdt->cache->root, name, namelen);
if (p)
ino = p->ino;
+ } else if (rdt->xinobits) {
+ ino = ovl_remap_lower_ino(ino, rdt->xinobits, rdt->fsid,
+ name, namelen);
}
return orig_ctx->actor(orig_ctx, name, namelen, offset, ino, d_type);
@@ -646,11 +673,16 @@ static int ovl_iterate_real(struct file *file, struct dir_context *ctx)
int err;
struct ovl_dir_file *od = file->private_data;
struct dentry *dir = file->f_path.dentry;
+ struct ovl_layer *lower_layer = ovl_layer_lower(dir);
struct ovl_readdir_translate rdt = {
.ctx.actor = ovl_fill_real,
.orig_ctx = ctx,
+ .xinobits = ovl_xino_bits(dir->d_sb),
};
+ if (rdt.xinobits && lower_layer)
+ rdt.fsid = lower_layer->fsid;
+
if (OVL_TYPE_MERGE(ovl_path_type(dir->d_parent))) {
struct kstat stat;
struct path statpath = file->f_path;
@@ -693,9 +725,10 @@ static int ovl_iterate(struct file *file, struct dir_context *ctx)
* dir is impure then need to adjust d_ino for copied up
* entries.
*/
- if (ovl_same_sb(dentry->d_sb) &&
- (ovl_test_flag(OVL_IMPURE, d_inode(dentry)) ||
- OVL_TYPE_MERGE(ovl_path_type(dentry->d_parent)))) {
+ if (ovl_xino_bits(dentry->d_sb) ||
+ (ovl_same_sb(dentry->d_sb) &&
+ (ovl_test_flag(OVL_IMPURE, d_inode(dentry)) ||
+ OVL_TYPE_MERGE(ovl_path_type(dentry->d_parent))))) {
return ovl_iterate_real(file, ctx);
}
return iterate_dir(od->realfile, ctx);
--
2.7.4
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