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ovl: decide if revalidate needed on a per-dentry basis

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Allow completely skipping ->revalidate() on a per-dentry basis, in case the
underlying layers used for a dentry do not themselves have ->revalidate().

E.g. negative overlay dentry has no underlying layers, hence revalidate is
unnecessary.  Or if lower layer is remote but overlay dentry is pure-upper,
then can skip revalidate.

The following places need to update whether the dentry needs revalidate or
not:

 - fill-super (root dentry)
 - lookup
 - create
 - fh_to_dentry

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Miklos Szeredi
2020-03-17 15:04:22 +01:00
parent 7925dad839
commit f428884456
6 changed files with 30 additions and 16 deletions
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21
fs/overlayfs/super.c
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@@ -158,11 +158,6 @@ static int ovl_dentry_weak_revalidate(struct dentry *dentry, unsigned int flags)
static const struct dentry_operations ovl_dentry_operations = {
.d_release = ovl_dentry_release,
.d_real = ovl_d_real,
};
static const struct dentry_operations ovl_reval_dentry_operations = {
.d_release = ovl_dentry_release,
.d_real = ovl_d_real,
.d_revalidate = ovl_dentry_revalidate,
.d_weak_revalidate = ovl_dentry_weak_revalidate,
};
@@ -779,7 +774,7 @@ static int ovl_check_namelen(struct path *path, struct ovl_fs *ofs,
}
static int ovl_lower_dir(const char *name, struct path *path,
struct ovl_fs *ofs, int *stack_depth, bool *remote)
struct ovl_fs *ofs, int *stack_depth)
{
int fh_type;
int err;
@@ -794,9 +789,6 @@ static int ovl_lower_dir(const char *name, struct path *path,
*stack_depth = max(*stack_depth, path->mnt->mnt_sb->s_stack_depth);
if (ovl_dentry_remote(path->dentry))
*remote = true;
/*
* The inodes index feature and NFS export need to encode and decode
* file handles, so they require that all layers support them.
@@ -1441,7 +1433,6 @@ static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb,
char *lowertmp, *lower;
struct path *stack = NULL;
unsigned int stacklen, numlower = 0, i;
bool remote = false;
struct ovl_entry *oe;
err = -ENOMEM;
@@ -1473,7 +1464,7 @@ static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb,
lower = lowertmp;
for (numlower = 0; numlower < stacklen; numlower++) {
err = ovl_lower_dir(lower, &stack[numlower], ofs,
&sb->s_stack_depth, &remote);
&sb->s_stack_depth);
if (err)
goto out_err;
@@ -1501,11 +1492,6 @@ static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb,
oe->lowerstack[i].layer = &ofs->layers[i+1];
}
if (remote)
sb->s_d_op = &ovl_reval_dentry_operations;
else
sb->s_d_op = &ovl_dentry_operations;
out:
for (i = 0; i < numlower; i++)
path_put(&stack[i]);
@@ -1623,6 +1609,7 @@ static struct dentry *ovl_get_root(struct super_block *sb,
ovl_dentry_set_flag(OVL_E_CONNECTED, root);
ovl_set_upperdata(d_inode(root));
ovl_inode_init(d_inode(root), &oip, ino, fsid);
ovl_dentry_update_reval(root, upperdentry, DCACHE_OP_WEAK_REVALIDATE);
return root;
}
@@ -1636,6 +1623,8 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
struct cred *cred;
int err;
sb->s_d_op = &ovl_dentry_operations;
err = -ENOMEM;
ofs = kzalloc(sizeof(struct ovl_fs), GFP_KERNEL);
if (!ofs)