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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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
fs/overlayfs/dir.c
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@ -243,6 +243,9 @@ static int ovl_instantiate(struct dentry *dentry, struct inode *inode,
ovl_dir_modified(dentry->d_parent, false);
ovl_dentry_set_upper_alias(dentry);
ovl_dentry_update_reval(dentry, newdentry,
DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE);
if (!hardlink) {
/*
* ovl_obtain_alias() can be called after ovl_create_real()

2
fs/overlayfs/export.c
View File

@ -324,6 +324,8 @@ static struct dentry *ovl_obtain_alias(struct super_block *sb,
if (upper_alias)
ovl_dentry_set_upper_alias(dentry);
}
ovl_dentry_update_reval(dentry, upper,
DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE);
return d_instantiate_anon(dentry, inode);

3
fs/overlayfs/namei.c
View File

@ -1077,6 +1077,9 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
goto out_free_oe;
}
ovl_dentry_update_reval(dentry, upperdentry,
DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE);
revert_creds(old_cred);
if (origin_path) {
dput(origin_path->dentry);

2
fs/overlayfs/overlayfs.h
View File

@ -230,6 +230,8 @@ bool ovl_index_all(struct super_block *sb);
bool ovl_verify_lower(struct super_block *sb);
struct ovl_entry *ovl_alloc_entry(unsigned int numlower);
bool ovl_dentry_remote(struct dentry *dentry);
void ovl_dentry_update_reval(struct dentry *dentry, struct dentry *upperdentry,
unsigned int mask);
bool ovl_dentry_weird(struct dentry *dentry);
enum ovl_path_type ovl_path_type(struct dentry *dentry);
void ovl_path_upper(struct dentry *dentry, struct path *path);

21
fs/overlayfs/super.c
View File

@ -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)

15
fs/overlayfs/util.c
View File

@ -96,6 +96,21 @@ bool ovl_dentry_remote(struct dentry *dentry)
(DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE);
}
void ovl_dentry_update_reval(struct dentry *dentry, struct dentry *upperdentry,
unsigned int mask)
{
struct ovl_entry *oe = OVL_E(dentry);
unsigned int i, flags = 0;
for (i = 0; i < oe->numlower; i++)
flags |= oe->lowerstack[i].dentry->d_flags;
spin_lock(&dentry->d_lock);
dentry->d_flags &= ~mask;
dentry->d_flags |= flags & mask;
spin_unlock(&dentry->d_lock);
}
bool ovl_dentry_weird(struct dentry *dentry)
{
return dentry->d_flags & (DCACHE_NEED_AUTOMOUNT |