starfive-tech/linux.git/fs/overlayfs, branch rt-linux-release

ovl: fix IOCB_DIRECT if underlying fs doesn't support direct IO

2021-09-28T07:16:12+00:00

Normally the check at open time suffices, but e.g loop device does set IOCB_DIRECT after doing its own checks (which are not sufficent for overlayfs). Make sure we don't call the underlying filesystem read/write method with the IOCB_DIRECT if it's not supported. Reported-by: Huang Jianan Fixes: 16914e6fc7e1 ("ovl: add ovl_read_iter()") Cc: # v4.19 Tested-by: Huang Jianan Signed-off-by: Miklos Szeredi

ovl: fix missing negative dentry check in ovl_rename()

2021-09-24T19:00:31+00:00

The following reproducer mkdir lower upper work merge touch lower/old touch lower/new mount -t overlay overlay -olowerdir=lower,upperdir=upper,workdir=work merge rm merge/new mv merge/old merge/new & unlink upper/new may result in this race: PROCESS A: rename("merge/old", "merge/new"); overwrite=true,ovl_lower_positive(old)=true, ovl_dentry_is_whiteout(new)=true -> flags |= RENAME_EXCHANGE PROCESS B: unlink("upper/new"); PROCESS A: lookup newdentry in new_upperdir call vfs_rename() with negative newdentry and RENAME_EXCHANGE Fix by adding the missing check for negative newdentry. Signed-off-by: Zheng Liang Fixes: e9be9d5e76e3 ("overlay filesystem") Cc: # v3.18 Signed-off-by: Miklos Szeredi

ovl: enable RCU'd ->get_acl()

2021-08-18T20:08:24+00:00

Overlayfs does not cache ACL's (to avoid double caching). Instead it just calls the underlying filesystem's i_op->get_acl(), which will return the cached value, if possible. In rcu path walk, however, get_cached_acl_rcu() is employed to get the value from the cache, which will fail on overlayfs resulting in dropping out of rcu walk mode. This can result in a big performance hit in certain situations. Fix by calling ->get_acl() with rcu=true in case of ACL_DONT_CACHE (which indicates pass-through) Reported-by: garyhuang Signed-off-by: Miklos Szeredi

vfs: add rcu argument to ->get_acl() callback

2021-08-18T20:08:24+00:00

Add a rcu argument to the ->get_acl() callback to allow get_cached_acl_rcu() to call the ->get_acl() method in the next patch. Signed-off-by: Miklos Szeredi

ovl: fix BUG_ON() in may_delete() when called from ovl_cleanup()

2021-08-17T15:37:53+00:00

If function ovl_instantiate() returns an error, ovl_cleanup will be called and try to remove newdentry from wdir, but the newdentry has been moved to udir at this time. This will causes BUG_ON(victim->d_parent->d_inode != dir) in fs/namei.c:may_delete. Signed-off-by: chenying Fixes: 01b39dcc9568 ("ovl: use inode_insert5() to hash a newly created inode") Link: https://lore.kernel.org/linux-unionfs/e6496a94-a161-dc04-c38a-d2544633acb4@bytedance.com/ Cc: # v4.18 Signed-off-by: Miklos Szeredi

ovl: use kvalloc in xattr copy-up

2021-08-17T09:47:45+00:00

Extended attributes are usually small, but could be up to 64k in size, so use the most efficient method for doing the allocation. Signed-off-by: Miklos Szeredi

ovl: update ctime when changing fileattr

2021-08-17T09:47:44+00:00

Currently we keep size, mode and times of overlay inode as the same as upper inode, so should update ctime when changing file attribution as well. Signed-off-by: Chengguang Xu Signed-off-by: Miklos Szeredi

ovl: skip checking lower file's i_writecount on truncate

2021-08-17T09:47:44+00:00

It is possible that a directory tree is shared between multiple overlay instances as a lower layer. In this case when one instance executes a file residing on the lower layer, the other instance denies a truncate(2) call on this file. This only happens for truncate(2) and not for open(2) with the O_TRUNC flag. Fix this interference and inconsistency by removing the preliminary i_writecount check before copy-up. This means that unlike on normal filesystems truncate(argv[0]) will now succeed. If this ever causes a regression in a real world use case this needs to be revisited. One way to fix this properly would be to keep a correct i_writecount in the overlay inode, but that is difficult due to memory mapping code only dealing with the real file/inode. Signed-off-by: Chengguang Xu Signed-off-by: Miklos Szeredi

ovl: relax lookup error on mismatch origin ftype

2021-08-17T09:47:44+00:00

We get occasional reports of lookup errors due to mismatched origin ftype from users that re-format a lower squashfs image. Commit 13c6ad0f45fd ("ovl: document lower modification caveats") tries to discourage the practice of re-formating lower layers and describes the expected behavior as undefined. Commit b0e0f69731cd ("ovl: restrict lower null uuid for "xino=auto"") limits the configurations in which origin file handles are followed. In addition to these measures, change the behavior in case of detecting a mismatch origin ftype in lookup to issue a warning, not follow origin, but not fail the lookup operation either. That should make overall more users happy without any big consequences. Link: https://lore.kernel.org/linux-unionfs/CAOQ4uxgPq9E9xxwU2CDyHy-_yCZZeymg+3n+-6AqkGGE1YtwvQ@mail.gmail.com/ Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: do not set overlay.opaque for new directories

2021-08-17T09:47:44+00:00

Enable optimizations only if user opted-in for any of extended features. If optimization is enabled, it breaks existing use case when a lower layer directory appears after directory was created on a merged layer. If overlay.opaque is applied, new files on lower layer are not visible. Consider the following scenario: - /lower and /upper are mounted to /merged - directory /merged/new-dir is created with a file test1 - overlay is unmounted - directory /lower/new-dir is created with a file test2 - overlay is mounted again If opaque is applied by default, file test2 is not going to be visible without explicitly clearing the overlay.opaque attribute Signed-off-by: Vyacheslav Yurkov Reviewed-by: Amir Goldstein Signed-off-by: Miklos Szeredi