Hi all, These patch set is the second version to add feature set support for overlayfs, have already been handle most suggestions from Amir in the last iteration. It do the following things. - Introduce compatible, read-only compatible and incompatible these three kinds of feature set which indicates the features in one layer (not the whole overlay image), save as __be64 bit mask on each layer's root directory via a "trusted.overlay.featre" xattr. - Kernel will refuse to mount if unknown incompatible feature are found in any one layer, and refuse to mount read-write if unknown ro-compatible feature are found in the upper layer. - Set feature bitset when redirect dir xattr, index and nfs_export feature were set or enabled. - Refer the layer which have feature set xattr as on-disk format v2, and the layer that don't have as on-disk format v1. - Introduce two Kconfig options (OVERLAY_FS_V2 and OVERLAY_FS_UPPER_V2) and the counterpart module and mount options. when OVERLAY_FS_V2 (or the counterpart module and mount option) is set, on-disk format v2 becomes necessary on all layers, when OVERLAY_FS_UPPER_V2 is set, on-disk format v2 is only necessary on the upper layer. - Check redirect dir feature when redirect xattr is found on the underlying directory, fsck.overlay is required if redirect dir feature missing. This patch set base on Linux-4.18-rc6 and is just request for comments, any comment is helpful, does not yet take care of the upcoming metadata copy-up feature and update the document, I can handle these in the next iteration. The counterpart fsck.overlay and mkfs.overlay program available here[*], You may want to review it together. From 8b540194 "fsck.overlay: factor out common header part from fsck" to the latest one d22ebd9a2 "mkfs.overlay: update README and turn on mkfs program", total 29 patches. I can post the tools patch set if you want. The fsck.overlay do the following: - Add "overlayfs_v2=<off/upper/on>" fsck option as same as mount option. - If "overlayfs_v2=off", fsck will ask user to create a new feature set xattr for on-disk format v1 layers, and will add the missing feature bit, but these are not required (except fix the corrupt feature set xattr). - If "overlayfs_v2=on", consistent feature set xattr are required for all layers, fsck will convert layer format v1 to v2 and ensure the consistency of the feature set on all layers. - If "overlayfs_v2=upper", release the requirement of feature set xattr on lower layers, but fsck will still warn if unrepaired corrupt feature xattr left over on the read-only lower layer. - Display features to human readable string. The mkfs.overlay do the following: - Create new feature set xattr for each underlying layer. - Do some basic check of the underlying layers, will refuse to make a new overlay iamge if an old overlayfs already existed or any one layer is mounted. - Accept redirect dir, index and nfs_export feature options, and set the corresponding feature bitset. - Use for new underlying layers only, doesn't give "force" options. Thanks, Yi. ------------------ [*] https://github.com/hisilicon/overlayfs-progs/commits/feature-set Changes since v1: - Feature set xattr contains features in one layer instead of the whole overlay image. - Use bitset to store features instead of readable string. - Compress all three kind of feature sets into one feature xattr instead of three xattrs. - Introduce on-disk format v2 which layer's feature set xatte becomes necessary and add two Kconfig options, two module options and two mount options to enable the requirement of on-disk format v2. - Do not auto fix redirect dir feature when redirect xattr was detected on directory, just give a warning message to teach user to run fsck. - Set redirect dir feature when overlayfs set redirect xattr on directory. zhangyi (F) (9): ovl: store ovl upper root path in ovl_fs ovl: read feature set from each layer's root dir ovl: check file system features can be mounted properly ovl: add helper funcs to set upper layer feature set ovl: add redirect dir feature when set redirect xattr to dir ovl: add index feature if index dir exists ovl: add nfs_export feature when nfs_export is enabled ovl: force mount underlying layers which have feature sets ovl: check redirect_dir feature when detect redirect xattr on dir fs/overlayfs/Kconfig | 40 +++++++ fs/overlayfs/Makefile | 2 +- fs/overlayfs/dir.c | 11 ++ fs/overlayfs/export.c | 12 +- fs/overlayfs/feature.c | 298 +++++++++++++++++++++++++++++++++++++++++++++++ fs/overlayfs/inode.c | 4 +- fs/overlayfs/namei.c | 35 +++++- fs/overlayfs/overlayfs.h | 99 ++++++++++++++++ fs/overlayfs/ovl_entry.h | 23 +++- fs/overlayfs/readdir.c | 2 +- fs/overlayfs/super.c | 118 ++++++++++++++++--- fs/overlayfs/util.c | 10 +- 12 files changed, 617 insertions(+), 37 deletions(-) create mode 100644 fs/overlayfs/feature.c -- 2.13.6 -- To unsubscribe from this list: send the line "unsubscribe linux-unionfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
