This series adds quota support to UBIFS. This series follows a very simple approach to quota: Neither the quota limits nor the quota usage are ever written to the medium. The quota usage is reconstructed from the filesystem during mount time. The quota limits must be set by the user each time after mount. This is probably not very convenient for systems that are used interactively, but UBIFS is targetted to embedded systems and here running a script after mount shouldn't be a problem. This of course isn't the way quota was thought to be, but I believe this is a good compromise for a feature that I predict is only rarely used on UBIFS. The big upside of this approach is that no on-disk format changes are required and thus we can't get any broken/corrupt filesystems because of quota support. Reconstructing the quota data each time during mount has an noticable but I think for many cases acceptable time overhead. I mounted a ~56MiB rootfs with 1920 files which takes around 0.7s longer when quota is enabled. As UBIFS works on mtd there is no block_device involved. The quotactl system call requires a path to a block device as argument. To overcome this we add support for passing the mount point instead. quota uses get_super_exclusive_thawed(), get_super_thawed() and get_super() to get hold of a super_block. All these functions require a block_device which we do not have for UBIFS, so this code has to be refactored a bit. I'm a bit outside of my comfort zone here, so please review carefully ;) The UBIFS quota support itself is based on a series by Dongsheng Yang posted here: http://lists.infradead.org/pipermail/linux-mtd/2015-September/061812.html This part hasn't changed much, except that the code for reading and writing quota files has been dropped. Sascha Dongsheng Yang (1): ubifs: Add quota support Sascha Hauer (10): quota: Make inode optional quota: Only module_put the format when existing fs: move __get_super() out of loop fs, quota: introduce wait_super_thawed() to wait until a superblock is thawed quota: Allow to pass quotactl a mountpoint ubifs: move checks and preparation into setflags() ubifs: Add support for FS_IOC_FS[SG]ETXATTR ioctls ubifs: do not ubifs_inode() on potentially NULL pointer ubifs: Add support for project id ubifs: export get_znode fs/quota/dquot.c | 9 +- fs/quota/quota.c | 79 ++++-- fs/super.c | 74 +++--- fs/ubifs/Makefile | 1 + fs/ubifs/dir.c | 31 ++- fs/ubifs/file.c | 43 +++ fs/ubifs/ioctl.c | 222 ++++++++++++++-- fs/ubifs/journal.c | 4 +- fs/ubifs/quota.c | 590 +++++++++++++++++++++++++++++++++++++++++ fs/ubifs/super.c | 46 +++- fs/ubifs/tnc.c | 34 +-- fs/ubifs/ubifs-media.h | 6 +- fs/ubifs/ubifs.h | 33 +++ include/linux/fs.h | 5 +- 14 files changed, 1076 insertions(+), 101 deletions(-) create mode 100644 fs/ubifs/quota.c -- 2.20.1
