6e135baed8
In this series, we've implemented transparent compression experimentally. It supports LZO and LZ4, but will add more later as we investigate in the field more. At this point, the feature doesn't expose compressed space to user directly in order to guarantee potential data updates later to the space. Instead, the main goal is to reduce data writes to flash disk as much as possible, resulting in extending disk life time as well as relaxing IO congestion. Alternatively, we're also considering to add ioctl() to reclaim compressed space and show it to user after putting the immutable bit. Enhancement: - add compression support - avoid unnecessary locks in quota ops - harden power-cut scenario for zoned block devices - use private bio_set to avoid IO congestion - replace GC mutex with rwsem to serialize callers Bug fix: - fix dentry consistency and memory corruption in rename()'s error case - fix wrong swap extent reports - fix casefolding bugs - change lock coverage to avoid deadlock - avoid GFP_KERNEL under f2fs_lock_op And, we've cleaned up sysfs entries to prepare no debugfs. -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEE00UqedjCtOrGVvQiQBSofoJIUNIFAl4zInwACgkQQBSofoJI UNL4Tg/+JBbVEFa3IUBGMdbjfgd/g0Jye++iMAYYGRWT6Ll/IGcHRV9NunITjgWU mBZqdhI28kXeiGCcewB1ZvivjLx22X4n6yevHk2B5A6PNe9IDCHi0HOAhJJHkjPH ecv2L+vX3Oj4y0+H7JNz9Fo3OIPJvMPtCQWlg1z+VQyhB85zNP7fZlvvIY4tG8yw ERo0YNotLqwcF1BxCwNbAhV3aJGDxar+MI//yNzpiwDX7IptVpqestfcoIYc9kKL 4kSWRyEIGwcuIeyoM6aofGS9t4Z/Oe/gdqcxNr6l5n0Q/tMTpb4b/fJFGNr6RRx9 X9NQo8flkQb2DEIOP0DVpO2aPebzsVtzg3LZUOLA83+wCHfwINtHai2Dy2zDJ2my BrVdou8fe2oxoaYihJg/Tz9cd0nA/6mZArtpYvDImAmX/xuGOvVk9zZkXNwc9nVX EyVzy0vW4lA6gAIJ95aG6DDhJcAtVoy0MhBRWG92Pufxhn9aW24AV63ChWUf9DRx /3RqpMAuQ3UC2gOxXKKnr54lsdhUIMn/y9sjROkVvQ1BvgRVxO8I4GFvMHMKv9pR 9KXiVRdzyYERyoL4+MF7A2zTnw+RHL4RVILa85p2ALGy2jQ1UuNUQi0BN9x2u1v8 S1ifNNX8SwOP+83ImFJhhn3HybpFQ45aLO3F7ZjKBQAnufJu+xw= =zeoY -----END PGP SIGNATURE----- Merge tag 'f2fs-for-5.6' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs Pull f2fs updates from Jaegeuk Kim: "In this series, we've implemented transparent compression experimentally. It supports LZO and LZ4, but will add more later as we investigate in the field more. At this point, the feature doesn't expose compressed space to user directly in order to guarantee potential data updates later to the space. Instead, the main goal is to reduce data writes to flash disk as much as possible, resulting in extending disk life time as well as relaxing IO congestion. Alternatively, we're also considering to add ioctl() to reclaim compressed space and show it to user after putting the immutable bit. Enhancements: - add compression support - avoid unnecessary locks in quota ops - harden power-cut scenario for zoned block devices - use private bio_set to avoid IO congestion - replace GC mutex with rwsem to serialize callers Bug fixes: - fix dentry consistency and memory corruption in rename()'s error case - fix wrong swap extent reports - fix casefolding bugs - change lock coverage to avoid deadlock - avoid GFP_KERNEL under f2fs_lock_op And, we've cleaned up sysfs entries to prepare no debugfs" * tag 'f2fs-for-5.6' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs: (31 commits) f2fs: fix race conditions in ->d_compare() and ->d_hash() f2fs: fix dcache lookup of !casefolded directories f2fs: Add f2fs stats to sysfs f2fs: delete duplicate information on sysfs nodes f2fs: change to use rwsem for gc_mutex f2fs: update f2fs document regarding to fsync_mode f2fs: add a way to turn off ipu bio cache f2fs: code cleanup for f2fs_statfs_project() f2fs: fix miscounted block limit in f2fs_statfs_project() f2fs: show the CP_PAUSE reason in checkpoint traces f2fs: fix deadlock allocating bio_post_read_ctx from mempool f2fs: remove unneeded check for error allocating bio_post_read_ctx f2fs: convert inline_dir early before starting rename f2fs: fix memleak of kobject f2fs: fix to add swap extent correctly f2fs: run fsck when getting bad inode during GC f2fs: support data compression f2fs: free sysfs kobject f2fs: declare nested quota_sem and remove unnecessary sems f2fs: don't put new_page twice in f2fs_rename ... |
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README
This directory attempts to document the ABI between the Linux kernel and userspace, and the relative stability of these interfaces. Due to the everchanging nature of Linux, and the differing maturity levels, these interfaces should be used by userspace programs in different ways. We have four different levels of ABI stability, as shown by the four different subdirectories in this location. Interfaces may change levels of stability according to the rules described below. The different levels of stability are: stable/ This directory documents the interfaces that the developer has defined to be stable. Userspace programs are free to use these interfaces with no restrictions, and backward compatibility for them will be guaranteed for at least 2 years. Most interfaces (like syscalls) are expected to never change and always be available. testing/ This directory documents interfaces that are felt to be stable, as the main development of this interface has been completed. The interface can be changed to add new features, but the current interface will not break by doing this, unless grave errors or security problems are found in them. Userspace programs can start to rely on these interfaces, but they must be aware of changes that can occur before these interfaces move to be marked stable. Programs that use these interfaces are strongly encouraged to add their name to the description of these interfaces, so that the kernel developers can easily notify them if any changes occur (see the description of the layout of the files below for details on how to do this.) obsolete/ This directory documents interfaces that are still remaining in the kernel, but are marked to be removed at some later point in time. The description of the interface will document the reason why it is obsolete and when it can be expected to be removed. removed/ This directory contains a list of the old interfaces that have been removed from the kernel. Every file in these directories will contain the following information: What: Short description of the interface Date: Date created KernelVersion: Kernel version this feature first showed up in. Contact: Primary contact for this interface (may be a mailing list) Description: Long description of the interface and how to use it. Users: All users of this interface who wish to be notified when it changes. This is very important for interfaces in the "testing" stage, so that kernel developers can work with userspace developers to ensure that things do not break in ways that are unacceptable. It is also important to get feedback for these interfaces to make sure they are working in a proper way and do not need to be changed further. How things move between levels: Interfaces in stable may move to obsolete, as long as the proper notification is given. Interfaces may be removed from obsolete and the kernel as long as the documented amount of time has gone by. Interfaces in the testing state can move to the stable state when the developers feel they are finished. They cannot be removed from the kernel tree without going through the obsolete state first. It's up to the developer to place their interfaces in the category they wish for it to start out in. Notable bits of non-ABI, which should not under any circumstances be considered stable: - Kconfig. Userspace should not rely on the presence or absence of any particular Kconfig symbol, in /proc/config.gz, in the copy of .config commonly installed to /boot, or in any invocation of the kernel build process. - Kernel-internal symbols. Do not rely on the presence, absence, location, or type of any kernel symbol, either in System.map files or the kernel binary itself. See Documentation/process/stable-api-nonsense.rst.