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ovl: consistent d_ino for non-samefs with xino 

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@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Amir Goldstein 2017-11-06 16:48:02 +02:00 committed by Miklos Szeredi
parent 12574a9f4c
commit adbf4f7ea8
1 changed files with 39 additions and 6 deletions
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45
fs/overlayfs/readdir.c
View File

@ -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);