On Tue, 2022-03-01 at 22:05 +0800, Xiubo Li wrote:
> On 3/1/22 9:31 PM, Jeff Layton wrote:
> > On Tue, 2022-03-01 at 19:30 +0800, xiubli@xxxxxxxxxx wrote:
> > > From: Xiubo Li <xiubli@xxxxxxxxxx>
> > >
> > > Signed-off-by: Xiubo Li <xiubli@xxxxxxxxxx>
> > > ---
> > > fs/ceph/dir.c | 66 +++++++++++++++++++++-----------------------
> > > fs/ceph/inode.c | 15 ++++++++++
> > > fs/ceph/mds_client.h | 1 +
> > > 3 files changed, 47 insertions(+), 35 deletions(-)
> > >
> > > diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
> > > index 6be0c1f793c2..e3917b4426e8 100644
> > > --- a/fs/ceph/dir.c
> > > +++ b/fs/ceph/dir.c
> > > @@ -316,8 +316,7 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
> > > int err;
> > > unsigned frag = -1;
> > > struct ceph_mds_reply_info_parsed *rinfo;
> > > - struct fscrypt_str tname = FSTR_INIT(NULL, 0);
> > > - struct fscrypt_str oname = FSTR_INIT(NULL, 0);
> > > + char *dentry_name = NULL;
> > >
> > > dout("readdir %p file %p pos %llx\n", inode, file, ctx->pos);
> > > if (dfi->file_info.flags & CEPH_F_ATEND)
> > > @@ -345,10 +344,6 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
> > > ctx->pos = 2;
> > > }
> > >
> > > - err = fscrypt_prepare_readdir(inode);
> > > - if (err)
> > > - goto out;
> > > -
> >
> > Why are you removing this? This is what ensures that the key is loaded
> > if we're going to need it.
>
> Since the dentry names are already decrypted in
> ceph_readdir_prepopulate(), and this patch is trying to avoid do the
> same thing again here after that.
>
> Because in ceph_readdir() this isn't needed any more. And in other
> places such as build path it will do it when needed.
>
> >
> > > spin_lock(&ci->i_ceph_lock);
> > > /* request Fx cap. if have Fx, we don't need to release Fs cap
> > > * for later create/unlink. */
> > > @@ -369,14 +364,6 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
> > > spin_unlock(&ci->i_ceph_lock);
> > > }
> > >
> > > - err = ceph_fname_alloc_buffer(inode, &tname);
> > > - if (err < 0)
> > > - goto out;
> > > -
> > > - err = ceph_fname_alloc_buffer(inode, &oname);
> > > - if (err < 0)
> > > - goto out;
> > > -
> > > /* proceed with a normal readdir */
> > > more:
> > > /* do we have the correct frag content buffered? */
> > > @@ -525,40 +512,49 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
> > > }
> > > }
> > > }
> > > +
> > > + dentry_name = kmalloc(280, GFP_KERNEL);
> > > + if (!dentry_name) {
> > > + err = -ENOMEM;
> > > + goto out;
> > > + }
> > > +
> > Woah, what's up with the bare "280" here?
>
> The long snap name in format of "_${ENCRYPTED-SNAP-NAME}_${INO}", the
> max length will be 1 +256 + 16.
>
Ok. Best to make a named constant definition for this then. Bare numbers
in an allocation like this make it hard to understand what's going on.
>
> >
> >
> > > for (; i < rinfo->dir_nr; i++) {
> > > struct ceph_mds_reply_dir_entry *rde = rinfo->dir_entries + i;
> > > - struct ceph_fname fname = { .dir = inode,
> > > - .name = rde->name,
> > > - .name_len = rde->name_len,
> > > - .ctext = rde->altname,
> > > - .ctext_len = rde->altname_len };
> > > - u32 olen = oname.len;
> > > -
> > > - err = ceph_fname_to_usr(&fname, &tname, &oname, NULL);
> > > - if (err) {
> > > - pr_err("%s unable to decode %.*s, got %d\n", __func__,
> > > - rde->name_len, rde->name, err);
> > > - goto out;
> > > - }
> > I may be missing something, but if you rip this out, where does the
> > decryption happen?
>
> In ceph_readdir_prepopulate(), and it will set the rde->dentry, and here
> we can get the name from the dentry directly instead of decrypt it again.
>
> >
> > > + struct dentry *dn = rde->dentry;
> > > + int name_len;
> > >
> > > BUG_ON(rde->offset < ctx->pos);
> > > BUG_ON(!rde->inode.in);
> > > + BUG_ON(!rde->dentry);
> > >
> > > ctx->pos = rde->offset;
> > > - dout("readdir (%d/%d) -> %llx '%.*s' %p\n",
> > > - i, rinfo->dir_nr, ctx->pos,
> > > - rde->name_len, rde->name, &rde->inode.in);
> > >
> > > - if (!dir_emit(ctx, oname.name, oname.len,
> > > + spin_lock(&dn->d_lock);
> > > + memcpy(dentry_name, dn->d_name.name, dn->d_name.len);
> > > + name_len = dn->d_name.len;
> > > + spin_unlock(&dn->d_lock);
> > > +
> > > + dentry_name[name_len] = '\0';
> > > + dout("readdir (%d/%d) -> %llx '%s' %p\n",
> > > + i, rinfo->dir_nr, ctx->pos, dentry_name, &rde->inode.in);
> > > +
> > > + dput(dn);
> > > + rde->dentry = NULL;
> > > +
> > > + if (!dir_emit(ctx, dentry_name, name_len,
> > > ceph_present_ino(inode->i_sb, le64_to_cpu(rde->inode.in->ino)),
> > > le32_to_cpu(rde->inode.in->mode) >> 12)) {
> > > dout("filldir stopping us...\n");
> > > err = 0;
> > > + for (; i < rinfo->dir_nr; i++) {
> > > + rde = rinfo->dir_entries + i;
> > > + dput(rde->dentry);
> > > + rde->dentry = NULL;
> > > + }
> > > goto out;
> > > }
> > >
> > > - /* Reset the lengths to their original allocated vals */
> > > - oname.len = olen;
> > > ctx->pos++;
> > > }
> > >
> > > @@ -616,8 +612,8 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
> > > err = 0;
> > > dout("readdir %p file %p done.\n", inode, file);
> > > out:
> > > - ceph_fname_free_buffer(inode, &tname);
> > > - ceph_fname_free_buffer(inode, &oname);
> > > + if (dentry_name)
> > > + kfree(dentry_name);
> > > return err;
> > > }
> > >
> > > diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
> > > index 2bc2f02b84e8..877e699fe43b 100644
> > > --- a/fs/ceph/inode.c
> > > +++ b/fs/ceph/inode.c
> > > @@ -1903,6 +1903,7 @@ int ceph_readdir_prepopulate(struct ceph_mds_request *req,
> > > goto out;
> > > }
> > >
> > > + rde->dentry = NULL;
> > > dname.name = oname.name;
> > > dname.len = oname.len;
> > > dname.hash = full_name_hash(parent, dname.name, dname.len);
> > > @@ -1963,6 +1964,12 @@ int ceph_readdir_prepopulate(struct ceph_mds_request *req,
> > > goto retry_lookup;
> > > }
> > >
> > > + /*
> > > + * ceph_readdir will use the dentry to get the name
> > > + * to avoid doing the dencrypt again there.
> > > + */
> > > + rde->dentry = dget(dn);
> > > +
> > > /* inode */
> > > if (d_really_is_positive(dn)) {
> > > in = d_inode(dn);
> > > @@ -2025,6 +2032,14 @@ int ceph_readdir_prepopulate(struct ceph_mds_request *req,
> > > dput(dn);
> > > }
> > > out:
> > > + if (err) {
> > > + for (; i >= 0; i--) {
> > > + struct ceph_mds_reply_dir_entry *rde;
> > > +
> > > + rde = rinfo->dir_entries + i;
> > > + dput(rde->dentry);
> > > + }
> > > + }
> > > if (err == 0 && skipped == 0) {
> > > set_bit(CEPH_MDS_R_DID_PREPOPULATE, &req->r_req_flags);
> > > req->r_readdir_cache_idx = cache_ctl.index;
> > > diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h
> > > index 0dfe24f94567..663d7754d57d 100644
> > > --- a/fs/ceph/mds_client.h
> > > +++ b/fs/ceph/mds_client.h
> > > @@ -96,6 +96,7 @@ struct ceph_mds_reply_info_in {
> > > };
> > >
> > > struct ceph_mds_reply_dir_entry {
> > > + struct dentry *dentry;
> > > char *name;
> > > u8 *altname;
> > > u32 name_len;
> >
> > NAK on this patch as it is...
> >
>
--
Jeff Layton <jlayton@xxxxxxxxxx>
