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ovl: reorder ovl_want_write() after ovl_inode_lock()

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Make the locking order of ovl_inode_lock() strictly between the two
vfs stacked layers, i.e.:
- ovl vfs locks: sb_writers, inode_lock, ...
- ovl_inode_lock
- upper vfs locks: sb_writers, inode_lock, ...

To that effect, move ovl_want_write() into the helpers ovl_nlink_start()
and ovl_copy_up_start which currently take the ovl_inode_lock() after
ovl_want_write().

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
This commit is contained in:
Amir Goldstein 2023-07-20 12:51:21 +03:00
parent d08d3b3c2c
commit 162d064440
5 changed files with 86 additions and 89 deletions
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13
fs/overlayfs/copy_up.c
View File

@ -1170,17 +1170,10 @@ static bool ovl_open_need_copy_up(struct dentry *dentry, int flags)
int ovl_maybe_copy_up(struct dentry *dentry, int flags)
{
int err = 0;
if (!ovl_open_need_copy_up(dentry, flags))
return 0;
if (ovl_open_need_copy_up(dentry, flags)) {
err = ovl_want_write(dentry);
if (!err) {
err = ovl_copy_up_flags(dentry, flags);
ovl_drop_write(dentry);
}
}
return err;
return ovl_copy_up_flags(dentry, flags);
}
int ovl_copy_up_with_data(struct dentry *dentry)

62
fs/overlayfs/dir.c
View File

@ -559,10 +559,6 @@ static int ovl_create_or_link(struct dentry *dentry, struct inode *inode,
struct cred *override_cred;
struct dentry *parent = dentry->d_parent;
err = ovl_copy_up(parent);
if (err)
return err;
old_cred = ovl_override_creds(dentry->d_sb);
/*
@ -626,6 +622,10 @@ static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev,
.link = link,
};
err = ovl_copy_up(dentry->d_parent);
if (err)
return err;
err = ovl_want_write(dentry);
if (err)
goto out;
@ -700,28 +700,24 @@ static int ovl_link(struct dentry *old, struct inode *newdir,
int err;
struct inode *inode;
err = ovl_want_write(old);
err = ovl_copy_up(old);
if (err)
goto out;
err = ovl_copy_up(old);
if (err)
goto out_drop_write;
err = ovl_copy_up(new->d_parent);
if (err)
goto out_drop_write;
goto out;
err = ovl_nlink_start(old);
if (err)
goto out;
if (ovl_is_metacopy_dentry(old)) {
err = ovl_set_link_redirect(old);
if (err)
goto out_drop_write;
goto out_nlink_end;
}
err = ovl_nlink_start(old);
if (err)
goto out_drop_write;
inode = d_inode(old);
ihold(inode);
@ -731,9 +727,8 @@ static int ovl_link(struct dentry *old, struct inode *newdir,
if (err)
iput(inode);
out_nlink_end:
ovl_nlink_end(old);
out_drop_write:
ovl_drop_write(old);
out:
return err;
}
@ -891,17 +886,13 @@ static int ovl_do_remove(struct dentry *dentry, bool is_dir)
goto out;
}
err = ovl_want_write(dentry);
err = ovl_copy_up(dentry->d_parent);
if (err)
goto out;
err = ovl_copy_up(dentry->d_parent);
if (err)
goto out_drop_write;
err = ovl_nlink_start(dentry);
if (err)
goto out_drop_write;
goto out;
old_cred = ovl_override_creds(dentry->d_sb);
if (!lower_positive)
@ -926,8 +917,6 @@ static int ovl_do_remove(struct dentry *dentry, bool is_dir)
if (ovl_dentry_upper(dentry))
ovl_copyattr(d_inode(dentry));
out_drop_write:
ovl_drop_write(dentry);
out:
ovl_cache_free(&list);
return err;
@ -1131,29 +1120,32 @@ static int ovl_rename(struct mnt_idmap *idmap, struct inode *olddir,
}
}
err = ovl_want_write(old);
err = ovl_copy_up(old);
if (err)
goto out;
err = ovl_copy_up(old);
if (err)
goto out_drop_write;
err = ovl_copy_up(new->d_parent);
if (err)
goto out_drop_write;
goto out;
if (!overwrite) {
err = ovl_copy_up(new);
if (err)
goto out_drop_write;
goto out;
} else if (d_inode(new)) {
err = ovl_nlink_start(new);
if (err)
goto out_drop_write;
goto out;
update_nlink = true;
}
if (!update_nlink) {
/* ovl_nlink_start() took ovl_want_write() */
err = ovl_want_write(old);
if (err)
goto out;
}
old_cred = ovl_override_creds(old->d_sb);
if (!list_empty(&list)) {
@ -1286,8 +1278,8 @@ out_revert_creds:
revert_creds(old_cred);
if (update_nlink)
ovl_nlink_end(new);
out_drop_write:
ovl_drop_write(old);
else
ovl_drop_write(old);
out:
dput(opaquedir);
ovl_cache_free(&list);

7
fs/overlayfs/export.c
View File

@ -23,12 +23,7 @@ static int ovl_encode_maybe_copy_up(struct dentry *dentry)
if (ovl_dentry_upper(dentry))
return 0;
err = ovl_want_write(dentry);
if (!err) {
err = ovl_copy_up(dentry);
ovl_drop_write(dentry);
}
err = ovl_copy_up(dentry);
if (err) {
pr_warn_ratelimited("failed to copy up on encode (%pd2, err=%i)\n",
dentry, err);

57
fs/overlayfs/inode.c
View File

@ -32,10 +32,6 @@ int ovl_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
if (err)
return err;
err = ovl_want_write(dentry);
if (err)
goto out;
if (attr->ia_valid & ATTR_SIZE) {
/* Truncate should trigger data copy up as well */
full_copy_up = true;
@ -54,7 +50,7 @@ int ovl_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
winode = d_inode(upperdentry);
err = get_write_access(winode);
if (err)
goto out_drop_write;
goto out;
}
if (attr->ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID))
@ -78,6 +74,10 @@ int ovl_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
*/
attr->ia_valid &= ~ATTR_OPEN;
err = ovl_want_write(dentry);
if (err)
goto out_put_write;
inode_lock(upperdentry->d_inode);
old_cred = ovl_override_creds(dentry->d_sb);
err = ovl_do_notify_change(ofs, upperdentry, attr);
@ -85,12 +85,12 @@ int ovl_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
if (!err)
ovl_copyattr(dentry->d_inode);
inode_unlock(upperdentry->d_inode);
ovl_drop_write(dentry);
out_put_write:
if (winode)
put_write_access(winode);
}
out_drop_write:
ovl_drop_write(dentry);
out:
return err;
}
@ -361,27 +361,27 @@ int ovl_xattr_set(struct dentry *dentry, struct inode *inode, const char *name,
struct path realpath;
const struct cred *old_cred;
err = ovl_want_write(dentry);
if (err)
goto out;
if (!value && !upperdentry) {
ovl_path_lower(dentry, &realpath);
old_cred = ovl_override_creds(dentry->d_sb);
err = vfs_getxattr(mnt_idmap(realpath.mnt), realdentry, name, NULL, 0);
revert_creds(old_cred);
if (err < 0)
goto out_drop_write;
goto out;
}
if (!upperdentry) {
err = ovl_copy_up(dentry);
if (err)
goto out_drop_write;
goto out;
realdentry = ovl_dentry_upper(dentry);
}
err = ovl_want_write(dentry);
if (err)
goto out;
old_cred = ovl_override_creds(dentry->d_sb);
if (value) {
err = ovl_do_setxattr(ofs, realdentry, name, value, size,
@ -391,12 +391,10 @@ int ovl_xattr_set(struct dentry *dentry, struct inode *inode, const char *name,
err = ovl_do_removexattr(ofs, realdentry, name);
}
revert_creds(old_cred);
ovl_drop_write(dentry);
/* copy c/mtime */
ovl_copyattr(inode);
out_drop_write:
ovl_drop_write(dentry);
out:
return err;
}
@ -611,10 +609,6 @@ static int ovl_set_or_remove_acl(struct dentry *dentry, struct inode *inode,
struct dentry *upperdentry = ovl_dentry_upper(dentry);
struct dentry *realdentry = upperdentry ?: ovl_dentry_lower(dentry);
err = ovl_want_write(dentry);
if (err)
return err;
/*
* If ACL is to be removed from a lower file, check if it exists in
* the first place before copying it up.
@ -630,7 +624,7 @@ static int ovl_set_or_remove_acl(struct dentry *dentry, struct inode *inode,
revert_creds(old_cred);
if (IS_ERR(real_acl)) {
err = PTR_ERR(real_acl);
goto out_drop_write;
goto out;
}
posix_acl_release(real_acl);
}
@ -638,23 +632,26 @@ static int ovl_set_or_remove_acl(struct dentry *dentry, struct inode *inode,
if (!upperdentry) {
err = ovl_copy_up(dentry);
if (err)
goto out_drop_write;
goto out;
realdentry = ovl_dentry_upper(dentry);
}
err = ovl_want_write(dentry);
if (err)
goto out;
old_cred = ovl_override_creds(dentry->d_sb);
if (acl)
err = ovl_do_set_acl(ofs, realdentry, acl_name, acl);
else
err = ovl_do_remove_acl(ofs, realdentry, acl_name);
revert_creds(old_cred);
ovl_drop_write(dentry);
/* copy c/mtime */
ovl_copyattr(inode);
out_drop_write:
ovl_drop_write(dentry);
out:
return err;
}
@ -778,14 +775,14 @@ int ovl_fileattr_set(struct mnt_idmap *idmap,
unsigned int flags;
int err;
err = ovl_want_write(dentry);
if (err)
goto out;
err = ovl_copy_up(dentry);
if (!err) {
ovl_path_real(dentry, &upperpath);
err = ovl_want_write(dentry);
if (err)
goto out;
old_cred = ovl_override_creds(inode->i_sb);
/*
* Store immutable/append-only flags in xattr and clear them
@ -798,6 +795,7 @@ int ovl_fileattr_set(struct mnt_idmap *idmap,
if (!err)
err = ovl_real_fileattr_set(&upperpath, fa);
revert_creds(old_cred);
ovl_drop_write(dentry);
/*
* Merge real inode flags with inode flags read from
@ -812,7 +810,6 @@ int ovl_fileattr_set(struct mnt_idmap *idmap,
/* Update ctime */
ovl_copyattr(inode);
}
ovl_drop_write(dentry);
out:
return err;
}

36
fs/overlayfs/util.c
View File

@ -676,16 +676,26 @@ int ovl_copy_up_start(struct dentry *dentry, int flags)
int err;
err = ovl_inode_lock_interruptible(inode);
if (!err && ovl_already_copied_up_locked(dentry, flags)) {
err = 1; /* Already copied up */
ovl_inode_unlock(inode);
}
if (err)
return err;
if (ovl_already_copied_up_locked(dentry, flags))
err = 1; /* Already copied up */
else
err = ovl_want_write(dentry);
if (err)
goto out_unlock;
return 0;
out_unlock:
ovl_inode_unlock(inode);
return err;
}
void ovl_copy_up_end(struct dentry *dentry)
{
ovl_drop_write(dentry);
ovl_inode_unlock(d_inode(dentry));
}
@ -1088,8 +1098,12 @@ int ovl_nlink_start(struct dentry *dentry)
if (err)
return err;
err = ovl_want_write(dentry);
if (err)
goto out_unlock;
if (d_is_dir(dentry) || !ovl_test_flag(OVL_INDEX, inode))
goto out;
return 0;
old_cred = ovl_override_creds(dentry->d_sb);
/*
@ -1100,10 +1114,15 @@ int ovl_nlink_start(struct dentry *dentry)
*/
err = ovl_set_nlink_upper(dentry);
revert_creds(old_cred);
out:
if (err)
ovl_inode_unlock(inode);
goto out_drop_write;
return 0;
out_drop_write:
ovl_drop_write(dentry);
out_unlock:
ovl_inode_unlock(inode);
return err;
}
@ -1120,6 +1139,7 @@ void ovl_nlink_end(struct dentry *dentry)
revert_creds(old_cred);
}
ovl_drop_write(dentry);
ovl_inode_unlock(inode);
}