- 03 Apr, 2009 40 commits
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git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-2.6-fscacheLinus Torvalds authored
* git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-2.6-fscache: (41 commits) NFS: Add mount options to enable local caching on NFS NFS: Display local caching state NFS: Store pages from an NFS inode into a local cache NFS: Read pages from FS-Cache into an NFS inode NFS: nfs_readpage_async() needs to be accessible as a fallback for local caching NFS: Add read context retention for FS-Cache to call back with NFS: FS-Cache page management NFS: Add some new I/O counters for FS-Cache doing things for NFS NFS: Invalidate FsCache page flags when cache removed NFS: Use local disk inode cache NFS: Define and create inode-level cache objects NFS: Define and create superblock-level objects NFS: Define and create server-level objects NFS: Register NFS for caching and retrieve the top-level index NFS: Permit local filesystem caching to be enabled for NFS NFS: Add FS-Cache option bit and debug bit NFS: Add comment banners to some NFS functions FS-Cache: Make kAFS use FS-Cache CacheFiles: A cache that backs onto a mounted filesystem CacheFiles: Export things for CacheFiles ...
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git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-2.6-dmLinus Torvalds authored
* git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-2.6-dm: (36 commits) dm: set queue ordered mode dm: move wait queue declaration dm: merge pushback and deferred bio lists dm: allow uninterruptible wait for pending io dm: merge __flush_deferred_io into caller dm: move bio_io_error into __split_and_process_bio dm: rename __split_bio dm: remove unnecessary struct dm_wq_req dm: remove unnecessary work queue context field dm: remove unnecessary work queue type field dm: bio list add bio_list_add_head dm snapshot: persistent fix dtr cleanup dm snapshot: move status to exception store dm snapshot: move ctr parsing to exception store dm snapshot: use DMEMIT macro for status dm snapshot: remove dm_snap header dm snapshot: remove dm_snap header use dm exception store: move cow pointer dm exception store: move chunk_fields dm exception store: move dm_target pointer ...
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git://git.open-osd.org/linux-open-osdLinus Torvalds authored
* 'for-linus' of git://git.open-osd.org/linux-open-osd: fs: Add exofs to Kernel build exofs: Documentation exofs: export_operations exofs: super_operations and file_system_type exofs: dir_inode and directory operations exofs: address_space_operations exofs: symlink_inode and fast_symlink_inode operations exofs: file and file_inode operations exofs: Kbuild, Headers and osd utils
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git://oss.sgi.com/xfs/xfsLinus Torvalds authored
* 'for-linus' of git://oss.sgi.com/xfs/xfs: (61 commits) Revert "xfs: increase the maximum number of supported ACL entries" xfs: cleanup uuid handling xfs: remove m_attroffset xfs: fix various typos xfs: pagecache usage optimization xfs: remove m_litino xfs: kill ino64 mount option xfs: kill mutex_t typedef xfs: increase the maximum number of supported ACL entries xfs: factor out code to find the longest free extent in the AG xfs: kill VN_BAD xfs: kill vn_atime_* helpers. xfs: cleanup xlog_bread xfs: cleanup xlog_recover_do_trans xfs: remove another leftover of the old inode log item format xfs: cleanup log unmount handling Fix xfs debug build breakage by pushing xfs_error.h after xfs: include header files for prototypes xfs: make symbols static xfs: move declaration to header file ...
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git://git.kernel.org/pub/scm/linux/kernel/git/kyle/parisc-2.6Linus Torvalds authored
* git://git.kernel.org/pub/scm/linux/kernel/git/kyle/parisc-2.6: (23 commits) parisc: move dereference_function_descriptor to process.c parisc: Move kernel Elf_Fdesc define to <asm/elf.h> parisc: fix build when ARCH_HAS_KMAP parisc: fix "make tar-pkg" parisc: drivers: fix warnings parisc: select BUG always parisc: asm/pdc.h should include asm/page.h parisc: led: remove proc_dir_entry::owner parisc: fix macro expansion in atomic.h parisc: iosapic: fix build breakage parisc: oops_enter()/oops_exit() in die() parisc: document light weight syscall ABI parisc: blink all or loadavg LEDs on oops parisc: add ftrace (function and graph tracer) functionality parisc: simplify sys_clone() parisc: add LATENCYTOP_SUPPORT and CONFIG_STACKTRACE_SUPPORT parisc: allow to build with 16k default kernel page size parisc: expose 32/64-bit capabilities in cpuinfo parisc: use constants instead of numbers in assembly parisc: fix usage of 32bit PTE page table entries on 32bit kernels ...
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git://git.kernel.org/pub/scm/linux/kernel/git/kyle/rtc-pariscLinus Torvalds authored
* git://git.kernel.org/pub/scm/linux/kernel/git/kyle/rtc-parisc: powerpc/ps3: Add rtc-ps3 powerpc: Hook up rtc-generic, and kill rtc-ppc m68k: Hook up rtc-generic parisc: rtc: Rename rtc-parisc to rtc-generic parisc: rtc: Add missing module alias parisc: rtc: platform_driver_probe() fixups parisc: rtc: get_rtc_time() returns unsigned int
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git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-udf-2.6Linus Torvalds authored
* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-udf-2.6: udf: Don't write integrity descriptor too often udf: Try anchor in block 256 first udf: Some type fixes and cleanups udf: use hardware sector size udf: fix novrs mount option udf: Fix oops when invalid character in filename occurs udf: return f_fsid for statfs(2) udf: Add checks to not underflow sector_t udf: fix default mode and dmode options handling udf: fix sparse warnings: udf: unsigned last[i] cannot be less than 0 udf: implement mode and dmode mounting options udf: reduce stack usage of udf_get_filename udf: reduce stack usage of udf_load_pvoldesc Fix the udf code not to pass structs on stack where possible. Remove struct typedefs from fs/udf/ecma_167.h et al.
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git://git.kernel.org/pub/scm/linux/kernel/git/davem/rcu-doc-2.6Linus Torvalds authored
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/rcu-doc-2.6: Doc: Fix spelling in RCU/rculist_nulls.txt. Doc: Fix wrong API example usage of call_rcu(). Doc: Fix missing whitespaces in RCU documentation.
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Akinobu Mita authored
Commit 7ca43e75 ("mm: use debug_kmap_atomic") introduced some debug_kmap_atomic() in wrong places. Signed-off-by:
Akinobu Mita <akinobu.mita@gmail.com> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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Kumar Gala authored
Commit f4112de6 ("mm: introduce debug_kmap_atomic") broke PPC builds with CONFIG_HIGHMEM=y: CC init/main.o In file included from include/linux/highmem.h:25, from include/linux/pagemap.h:11, from include/linux/mempolicy.h:63, from init/main.c:53: arch/powerpc/include/asm/highmem.h: In function 'kmap_atomic_prot': arch/powerpc/include/asm/highmem.h:98: error: implicit declaration of function 'debug_kmap_atomic' In file included from include/linux/pagemap.h:11, from include/linux/mempolicy.h:63, from init/main.c:53: include/linux/highmem.h: At top level: include/linux/highmem.h:196: warning: conflicting types for 'debug_kmap_atomic' include/linux/highmem.h:196: error: static declaration of 'debug_kmap_atomic' follows non-static declaration include/asm/highmem.h:98: error: previous implicit declaration of 'debug_kmap_atomic' was here make[1]: *** [init/main.o] Error 1 make: *** [init] Error 2 Signed-off-by:
Kumar Gala <galak@kernel.crashing.org> Acked-by:
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git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6Linus Torvalds authored
* git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6: crypto: ixp4xx - Fix handling of chained sg buffers crypto: shash - Fix unaligned calculation with short length hwrng: timeriomem - Use phys address rather than virt
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git://git.kernel.org/pub/scm/linux/kernel/git/gerg/m68knommuLinus Torvalds authored
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/gerg/m68knommu: (41 commits) m68knommu: improve compile arch switch settings m68knommu: fix 5407 ColdFire UART vector setup m68knommu: fix 5307 ColdFire UART vector setup m68knommu: fix 5249 ColdFire UART vector setup m68knommu: fix 5249 ColdFire UART setup m68knommu: fix end of uart table marker m68knommu: switch to using generic_handle_irq() m68k: merge the mmu and non-mmu versions of tlbflush.h m68knommu: introduce basic clk infrastructure m68k: merge the mmu and non-mmu versions of module.h m68knommu: add missing interrupt line definition for UART 2 m68k: merge the mmu and non-mmu versions of mmu_context.h m68k: merge the mmu and non-mmu versions of current.h m68k: merge the mmu and non-mmu versions of div64.h m68k: merge the mmu and non-mmu versions of bugs.h m68k: merge the mmu and non-mmu versions of bug.h m68k: use the mmu version of cache.h for m68knommu as well m68k: use the mmu version of bootinfo.h for m68knommu as well m68k: merge the mmu and non-mmu versions of fb.h m68k: merge the mmu and non-mmu versions of segment.h ...
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git://neil.brown.name/mdLinus Torvalds authored
* 'for-linus' of git://neil.brown.name/md: (53 commits) md/raid5 revise rules for when to update metadata during reshape md/raid5: minor code cleanups in make_request. md: remove CONFIG_MD_RAID_RESHAPE config option. md/raid5: be more careful about write ordering when reshaping. md: don't display meaningless values in sysfs files resync_start and sync_speed md/raid5: allow layout and chunksize to be changed on active array. md/raid5: reshape using largest of old and new chunk size md/raid5: prepare for allowing reshape to change layout md/raid5: prepare for allowing reshape to change chunksize. md/raid5: clearly differentiate 'before' and 'after' stripes during reshape. Documentation/md.txt update md: allow number of drives in raid5 to be reduced md/raid5: change reshape-progress measurement to cope with reshaping backwards. md: add explicit method to signal the end of a reshape. md/raid5: enhance raid5_size to work correctly with negative delta_disks md/raid5: drop qd_idx from r6_state md/raid6: move raid6 data processing to raid6_pq.ko md: raid5 run(): Fix max_degraded for raid level 4. md: 'array_size' sysfs attribute md: centralize ->array_sectors modifications ...
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Linus Torvalds authored
* master.kernel.org:/home/rmk/linux-2.6-arm: [ARM] fix build-breaking 7a192ec3 commit ARM: Add SMSC911X support to Overo platform (V2) arm: update omap_ldp defconfig to use smsc911x arm: update realview defconfigs to use smsc911x arm: update pcm037 defconfig to use smsc911x arm: convert omap ldp platform to use smsc911x arm: convert realview platform to use smsc911x arm: convert pcm037 platform to use smsc911x [ARM] 5444/1: ARM: Realview: Fix event-device multiplicators in localtimer.c [ARM] 5442/1: pxa/cm-x255: fix reverse RDY gpios in PCMCIA driver [ARM] 5441/1: Use pr_err on error paths in at91 pm [ARM] 5440/1: Fix VFP state corruption due to preemption during VFP exceptions [ARM] 5439/1: Do not clear bit 10 of DFSR during abort handling on ARMv6 [ARM] 5437/1: Add documentation for "nohlt" kernel parameter [ARM] 5436/1: ARM: OMAP: Fix compile for rx51 [ARM] arch_reset() now takes a second parameter [ARM] Kirkwood: small L2 code cleanup [ARM] Kirkwood: invalidate L2 cache before enabling it
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git://git.kernel.org/pub/scm/linux/kernel/git/bart/linux-hdreg-h-cleanupLinus Torvalds authored
* git://git.kernel.org/pub/scm/linux/kernel/git/bart/linux-hdreg-h-cleanup: remove <linux/ata.h> include from <linux/hdreg.h> include/linux/hdreg.h: remove unused defines isd200: use ATA_* defines instead of *_STAT and *_ERR ones include/linux/hdreg.h: cover WIN_* and friends with #ifndef/#endif __KERNEL__ aoe: WIN_* -> ATA_CMD_* isd200: WIN_* -> ATA_CMD_* include/linux/hdreg.h: cover struct hd_driveid with #ifndef/#endif __KERNEL__ xsysace: make it 'struct hd_driveid'-free ubd_kern: make it 'struct hd_driveid'-free isd200: make it 'struct hd_driveid'-free
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David Howells authored
Add NFS mount options to allow the local caching support to be enabled. The attached patch makes it possible for the NFS filesystem to be told to make use of the network filesystem local caching service (FS-Cache). To be able to use this, a recent nfsutils package is required. There are three variant NFS mount options that can be added to a mount command to control caching for a mount. Only the last one specified takes effect: (*) Adding "fsc" will request caching. (*) Adding "fsc=<string>" will request caching and also specify a uniquifier. (*) Adding "nofsc" will disable caching. For example: mount warthog:/ /a -o fsc The cache of a particular superblock (NFS FSID) will be shared between all mounts of that volume, provided they have the same connection parameters and are not marked 'nosharecache'. Where it is otherwise impossible to distinguish superblocks because all the parameters are identical, but the 'nosharecache' option is supplied, a uniquifying string must be supplied, else only the first mount will be permitted to use the cache. If there's a key collision, then the second mount will disable caching and give a warning into the kernel log. Signed-off-by:
David Howells <dhowells@redhat.com> Acked-by:
Steve Dickson <steved@redhat.com> Acked-by:
Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by:
Al Viro <viro@zeniv.linux.org.uk> Tested-by:
Daire Byrne <Daire.Byrne@framestore.com>
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David Howells authored
Display the local caching state in /proc/fs/nfsfs/volumes. Signed-off-by:
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David Howells authored
Store pages from an NFS inode into the cache data storage object associated with that inode. Signed-off-by:
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David Howells authored
Read pages from an FS-Cache data storage object representing an inode into an NFS inode. Signed-off-by:
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David Howells authored
nfs_readpage_async() needs to be non-static so that it can be used as a fallback for the local on-disk caching should an EIO crop up when reading the cache. Signed-off-by:
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David Howells authored
Add read context retention so that FS-Cache can call back into NFS when a read operation on the cache fails EIO rather than reading data. This permits NFS to then fetch the data from the server instead using the appropriate security context. Signed-off-by:
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David Howells authored
FS-Cache page management for NFS. This includes hooking the releasing and invalidation of pages marked with PG_fscache (aka PG_private_2) and waiting for completion of the write-to-cache flag (PG_fscache_write aka PG_owner_priv_2). Signed-off-by:
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David Howells authored
Add some new NFS I/O counters for FS-Cache doing things for NFS. A new line is emitted into /proc/pid/mountstats if caching is enabled that looks like: fsc: <rok> <rfl> <wok> <wfl> <unc> Where <rok> is the number of pages read successfully from the cache, <rfl> is the number of failed page reads against the cache, <wok> is the number of successful page writes to the cache, <wfl> is the number of failed page writes to the cache, and <unc> is the number of NFS pages that have been disconnected from the cache. Signed-off-by:
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David Howells authored
Invalidate the FsCache page flags on the pages belonging to an inode when the cache backing that NFS inode is removed. This allows a live cache to be withdrawn. Signed-off-by:
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David Howells authored
Bind data storage objects in the local cache to NFS inodes. Signed-off-by:
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David Howells authored
Define and create inode-level cache data storage objects (as managed by nfs_inode structs). Each inode-level object is created in a superblock-level index object and is itself a data storage object into which pages from the inode are stored. The inode object key is the NFS file handle for the inode. The inode object is given coherency data to carry in the auxiliary data permitted by the cache. This is a sequence made up of: (1) i_mtime from the NFS inode. (2) i_ctime from the NFS inode. (3) i_size from the NFS inode. (4) change_attr from the NFSv4 attribute data. As the cache is a persistent cache, the auxiliary data is checked when a new NFS in-memory inode is set up that matches an already existing data storage object in the cache. If the coherency data is the same, the on-disk object is retained and used; if not, it is scrapped and a new one created. Signed-off-by:
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David Howells authored
Define and create superblock-level cache index objects (as managed by nfs_server structs). Each superblock object is created in a server level index object and is itself an index into which inode-level objects are inserted. Ideally there would be one superblock-level object per server, and the former would be folded into the latter; however, since the "nosharecache" option exists this isn't possible. The superblock object key is a sequence consisting of: (1) Certain superblock s_flags. (2) Various connection parameters that serve to distinguish superblocks for sget(). (3) The volume FSID. (4) The security flavour. (5) The uniquifier length. (6) The uniquifier text. This is normally an empty string, unless the fsc=xyz mount option was used to explicitly specify a uniquifier. The key blob is of variable length, depending on the length of (6). The superblock object is given no coherency data to carry in the auxiliary data permitted by the cache. It is assumed that the superblock is always coherent. This patch also adds uniquification handling such that two otherwise identical superblocks, at least one of which is marked "nosharecache", won't end up trying to share the on-disk cache. It will be possible to manually provide a uniquifier through a mount option with a later patch to avoid the error otherwise produced. Signed-off-by: -
David Howells authored
Define and create server-level cache index objects (as managed by nfs_client structs). Each server object is created in the NFS top-level index object and is itself an index into which superblock-level objects are inserted. Ideally there would be one superblock-level object per server, and the former would be folded into the latter; however, since the "nosharecache" option exists this isn't possible. The server object key is a sequence consisting of: (1) NFS version (2) Server address family (eg: AF_INET or AF_INET6) (3) Server port. (4) Server IP address. The key blob is of variable length, depending on the length of (4). The server object is given no coherency data to carry in the auxiliary data permitted by the cache. Signed-off-by:
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David Howells authored
Register NFS for caching and retrieve the top-level cache index object cookie. Signed-off-by:
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David Howells authored
Permit local filesystem caching to be enabled for NFS in the kernel configuration. Signed-off-by:
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David Howells authored
Add FS-Cache option bit to nfs_server struct. This is set to indicate local on-disk caching is enabled for a particular superblock. Also add debug bit for local caching operations. Signed-off-by:
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David Howells authored
Add comment banners to some NFS functions so that they can be modified by the NFS fscache patches for further information. Signed-off-by:
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David Howells authored
The attached patch makes the kAFS filesystem in fs/afs/ use FS-Cache, and through it any attached caches. The kAFS filesystem will use caching automatically if it's available. Signed-off-by:
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David Howells authored
Add an FS-Cache cache-backend that permits a mounted filesystem to be used as a backing store for the cache. CacheFiles uses a userspace daemon to do some of the cache management - such as reaping stale nodes and culling. This is called cachefilesd and lives in /sbin. The source for the daemon can be downloaded from: http://people.redhat.com/~dhowells/cachefs/cachefilesd.c And an example configuration from: http://people.redhat.com/~dhowells/cachefs/cachefilesd.conf The filesystem and data integrity of the cache are only as good as those of the filesystem providing the backing services. Note that CacheFiles does not attempt to journal anything since the journalling interfaces of the various filesystems are very specific in nature. CacheFiles creates a misc character device - "/dev/cachefiles" - that is used to communication with the daemon. Only one thing may have this open at once, and whilst it is open, a cache is at least partially in existence. The daemon opens this and sends commands down it to control the cache. CacheFiles is currently limited to a single cache. CacheFiles attempts to maintain at least a certain percentage of free space on the filesystem, shrinking the cache by culling the objects it contains to make space if necessary - see the "Cache Culling" section. This means it can be placed on the same medium as a live set of data, and will expand to make use of spare space and automatically contract when the set of data requires more space. ============ REQUIREMENTS ============ The use of CacheFiles and its daemon requires the following features to be available in the system and in the cache filesystem: - dnotify. - extended attributes (xattrs). - openat() and friends. - bmap() support on files in the filesystem (FIBMAP ioctl). - The use of bmap() to detect a partial page at the end of the file. It is strongly recommended that the "dir_index" option is enabled on Ext3 filesystems being used as a cache. ============= CONFIGURATION ============= The cache is configured by a script in /etc/cachefilesd.conf. These commands set up cache ready for use. The following script commands are available: (*) brun <N>% (*) bcull <N>% (*) bstop <N>% (*) frun <N>% (*) fcull <N>% (*) fstop <N>% Configure the culling limits. Optional. See the section on culling The defaults are 7% (run), 5% (cull) and 1% (stop) respectively. The commands beginning with a 'b' are file space (block) limits, those beginning with an 'f' are file count limits. (*) dir <path> Specify the directory containing the root of the cache. Mandatory. (*) tag <name> Specify a tag to FS-Cache to use in distinguishing multiple caches. Optional. The default is "CacheFiles". (*) debug <mask> Specify a numeric bitmask to control debugging in the kernel module. Optional. The default is zero (all off). The following values can be OR'd into the mask to collect various information: 1 Turn on trace of function entry (_enter() macros) 2 Turn on trace of function exit (_leave() macros) 4 Turn on trace of internal debug points (_debug()) This mask can also be set through sysfs, eg: echo 5 >/sys/modules/cachefiles/parameters/debug ================== STARTING THE CACHE ================== The cache is started by running the daemon. The daemon opens the cache device, configures the cache and tells it to begin caching. At that point the cache binds to fscache and the cache becomes live. The daemon is run as follows: /sbin/cachefilesd [-d]* [-s] [-n] [-f <configfile>] The flags are: (*) -d Increase the debugging level. This can be specified multiple times and is cumulative with itself. (*) -s Send messages to stderr instead of syslog. (*) -n Don't daemonise and go into background. (*) -f <configfile> Use an alternative configuration file rather than the default one. =============== THINGS TO AVOID =============== Do not mount other things within the cache as this will cause problems. The kernel module contains its own very cut-down path walking facility that ignores mountpoints, but the daemon can't avoid them. Do not create, rename or unlink files and directories in the cache whilst the cache is active, as this may cause the state to become uncertain. Renaming files in the cache might make objects appear to be other objects (the filename is part of the lookup key). Do not change or remove the extended attributes attached to cache files by the cache as this will cause the cache state management to get confused. Do not create files or directories in the cache, lest the cache get confused or serve incorrect data. Do not chmod files in the cache. The module creates things with minimal permissions to prevent random users being able to access them directly. ============= CACHE CULLING ============= The cache may need culling occasionally to make space. This involves discarding objects from the cache that have been used less recently than anything else. Culling is based on the access time of data objects. Empty directories are culled if not in use. Cache culling is done on the basis of the percentage of blocks and the percentage of files available in the underlying filesystem. There are six "limits": (*) brun (*) frun If the amount of free space and the number of available files in the cache rises above both these limits, then culling is turned off. (*) bcull (*) fcull If the amount of available space or the number of available files in the cache falls below either of these limits, then culling is started. (*) bstop (*) fstop If the amount of available space or the number of available files in the cache falls below either of these limits, then no further allocation of disk space or files is permitted until culling has raised things above these limits again. These must be configured thusly: 0 <= bstop < bcull < brun < 100 0 <= fstop < fcull < frun < 100 Note that these are percentages of available space and available files, and do _not_ appear as 100 minus the percentage displayed by the "df" program. The userspace daemon scans the cache to build up a table of cullable objects. These are then culled in least recently used order. A new scan of the cache is started as soon as space is made in the table. Objects will be skipped if their atimes have changed or if the kernel module says it is still using them. =============== CACHE STRUCTURE =============== The CacheFiles module will create two directories in the directory it was given: (*) cache/ (*) graveyard/ The active cache objects all reside in the first directory. The CacheFiles kernel module moves any retired or culled objects that it can't simply unlink to the graveyard from which the daemon will actually delete them. The daemon uses dnotify to monitor the graveyard directory, and will delete anything that appears therein. The module represents index objects as directories with the filename "I..." or "J...". Note that the "cache/" directory is itself a special index. Data objects are represented as files if they have no children, or directories if they do. Their filenames all begin "D..." or "E...". If represented as a directory, data objects will have a file in the directory called "data" that actually holds the data. Special objects are similar to data objects, except their filenames begin "S..." or "T...". If an object has children, then it will be represented as a directory. Immediately in the representative directory are a collection of directories named for hash values of the child object keys with an '@' prepended. Into this directory, if possible, will be placed the representations of the child objects: INDEX INDEX INDEX DATA FILES ========= ========== ================================= ================ cache/@4a/I03nfs/@30/Ji000000000000000--fHg8hi8400 cache/@4a/I03nfs/@30/Ji000000000000000--fHg8hi8400/@75/Es0g000w...DB1ry cache/@4a/I03nfs/@30/Ji000000000000000--fHg8hi8400/@75/Es0g000w...N22ry cache/@4a/I03nfs/@30/Ji000000000000000--fHg8hi8400/@75/Es0g000w...FP1ry If the key is so long that it exceeds NAME_MAX with the decorations added on to it, then it will be cut into pieces, the first few of which will be used to make a nest of directories, and the last one of which will be the objects inside the last directory. The names of the intermediate directories will have '+' prepended: J1223/@23/+xy...z/+kl...m/Epqr Note that keys are raw data, and not only may they exceed NAME_MAX in size, they may also contain things like '/' and NUL characters, and so they may not be suitable for turning directly into a filename. To handle this, CacheFiles will use a suitably printable filename directly and "base-64" encode ones that aren't directly suitable. The two versions of object filenames indicate the encoding: OBJECT TYPE PRINTABLE ENCODED =============== =============== =============== Index "I..." "J..." Data "D..." "E..." Special "S..." "T..." Intermediate directories are always "@" or "+" as appropriate. Each object in the cache has an extended attribute label that holds the object type ID (required to distinguish special objects) and the auxiliary data from the netfs. The latter is used to detect stale objects in the cache and update or retire them. Note that CacheFiles will erase from the cache any file it doesn't recognise or any file of an incorrect type (such as a FIFO file or a device file). ========================== SECURITY MODEL AND SELINUX ========================== CacheFiles is implemented to deal properly with the LSM security features of the Linux kernel and the SELinux facility. One of the problems that CacheFiles faces is that it is generally acting on behalf of a process, and running in that process's context, and that includes a security context that is not appropriate for accessing the cache - either because the files in the cache are inaccessible to that process, or because if the process creates a file in the cache, that file may be inaccessible to other processes. The way CacheFiles works is to temporarily change the security context (fsuid, fsgid and actor security label) that the process acts as - without changing the security context of the process when it the target of an operation performed by some other process (so signalling and suchlike still work correctly). When the CacheFiles module is asked to bind to its cache, it: (1) Finds the security label attached to the root cache directory and uses that as the security label with which it will create files. By default, this is: cachefiles_var_t (2) Finds the security label of the process which issued the bind request (presumed to be the cachefilesd daemon), which by default will be: cachefilesd_t and asks LSM to supply a security ID as which it should act given the daemon's label. By default, this will be: cachefiles_kernel_t SELinux transitions the daemon's security ID to the module's security ID based on a rule of this form in the policy. type_transition <daemon's-ID> kernel_t : process <module's-ID>; For instance: type_transition cachefilesd_t kernel_t : process cachefiles_kernel_t; The module's security ID gives it permission to create, move and remove files and directories in the cache, to find and access directories and files in the cache, to set and access extended attributes on cache objects, and to read and write files in the cache. The daemon's security ID gives it only a very restricted set of permissions: it may scan directories, stat files and erase files and directories. It may not read or write files in the cache, and so it is precluded from accessing the data cached therein; nor is it permitted to create new files in the cache. There are policy source files available in: http://people.redhat.com/~dhowells/fscache/cachefilesd-0.8.tar.bz2 and later versions. In that tarball, see the files: cachefilesd.te cachefilesd.fc cachefilesd.if They are built and installed directly by the RPM. If a non-RPM based system is being used, then copy the above files to their own directory and run: make -f /usr/share/selinux/devel/Makefile semodule -i cachefilesd.pp You will need checkpolicy and selinux-policy-devel installed prior to the build. By default, the cache is located in /var/fscache, but if it is desirable that it should be elsewhere, than either the above policy files must be altered, or an auxiliary policy must be installed to label the alternate location of the cache. For instructions on how to add an auxiliary policy to enable the cache to be located elsewhere when SELinux is in enforcing mode, please see: /usr/share/doc/cachefilesd-*/move-cache.txt When the cachefilesd rpm is installed; alternatively, the document can be found in the sources. ================== A NOTE ON SECURITY ================== CacheFiles makes use of the split security in the task_struct. It allocates its own task_security structure, and redirects current->act_as to point to it when it acts on behalf of another process, in that process's context. The reason it does this is that it calls vfs_mkdir() and suchlike rather than bypassing security and calling inode ops directly. Therefore the VFS and LSM may deny the CacheFiles access to the cache data because under some circumstances the caching code is running in the security context of whatever process issued the original syscall on the netfs. Furthermore, should CacheFiles create a file or directory, the security parameters with that object is created (UID, GID, security label) would be derived from that process that issued the system call, thus potentially preventing other processes from accessing the cache - including CacheFiles's cache management daemon (cachefilesd). What is required is to temporarily override the security of the process that issued the system call. We can't, however, just do an in-place change of the security data as that affects the process as an object, not just as a subject. This means it may lose signals or ptrace events for example, and affects what the process looks like in /proc. So CacheFiles makes use of a logical split in the security between the objective security (task->sec) and the subjective security (task->act_as). The objective security holds the intrinsic security properties of a process and is never overridden. This is what appears in /proc, and is what is used when a process is the target of an operation by some other process (SIGKILL for example). The subjective security holds the active security properties of a process, and may be overridden. This is not seen externally, and is used whan a process acts upon another object, for example SIGKILLing another process or opening a file. LSM hooks exist that allow SELinux (or Smack or whatever) to reject a request for CacheFiles to run in a context of a specific security label, or to create files and directories with another security label. This documentation is added by the patch to: Documentation/filesystems/caching/cachefiles.txt Signed-Off-By:
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David Howells authored
Export a number of functions for CacheFiles's use. Signed-off-by:
Rik van Riel <riel@redhat.com> Acked-by:
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David Howells authored
Add a function to install a monitor on the page lock waitqueue for a particular page, thus allowing the page being unlocked to be detected. This is used by CacheFiles to detect read completion on a page in the backing filesystem so that it can then copy the data to the waiting netfs page. Signed-off-by:
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David Howells authored
Implement the data I/O part of the FS-Cache netfs API. The documentation and API header file were added in a previous patch. This patch implements the following functions for the netfs to call: (*) fscache_attr_changed(). Indicate that the object has changed its attributes. The only attribute currently recorded is the file size. Only pages within the set file size will be stored in the cache. This operation is submitted for asynchronous processing, and will return immediately. It will return -ENOMEM if an out of memory error is encountered, -ENOBUFS if the object is not actually cached, or 0 if the operation is successfully queued. (*) fscache_read_or_alloc_page(). (*) fscache_read_or_alloc_pages(). Request data be fetched from the disk, and allocate internal metadata to track the netfs pages and reserve disk space for unknown pages. These operations perform semi-asynchronous data reads. Upon returning they will indicate which pages they think can be retrieved from disk, and will have set in progress attempts to retrieve those pages. These will return, in order of preference, -ENOMEM on memory allocation error, -ERESTARTSYS if a signal interrupted proceedings, -ENODATA if one or more requested pages are not yet cached, -ENOBUFS if the object is not actually cached or if there isn't space for future pages to be cached on this object, or 0 if successful. In the case of the multipage function, the pages for which reads are set in progress will be removed from the list and the page count decreased appropriately. If any read operations should fail, the completion function will be given an error, and will also be passed contextual information to allow the netfs to fall back to querying the server for the absent pages. For each successful read, the page completion function will also be called. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_alloc_page(). Allocate internal metadata to track a netfs page and reserve disk space. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't enough space in the cache, or 0 if successful. Any pages subsequently tracked by the cache will have PG_fscache set upon them on return. fscache_uncache_page() must be called for such pages. If supplied by the netfs, the mark_pages_cached() cookie op will be invoked for any pages now tracked. (*) fscache_write_page(). Request data be stored to disk. This may only be called on pages that have been read or alloc'd by the above three functions and have not yet been uncached. This will return -ENOMEM on memory allocation error, -ERESTARTSYS on signal, -ENOBUFS if the object isn't cached, or there isn't immediately enough space in the cache, or 0 if successful. On a successful return, this operation will have queued the page for asynchronous writing to the cache. The page will be returned with PG_fscache_write set until the write completes one way or another. The caller will not be notified if the write fails due to an I/O error. If that happens, the object will become available and all pending writes will be aborted. Note that the cache may batch up page writes, and so it may take a while to get around to writing them out. The caller must assume that until PG_fscache_write is cleared the page is use by the cache. Any changes made to the page may be reflected on disk. The page may even be under DMA. (*) fscache_uncache_page(). Indicate that the cache should stop tracking a page previously read or alloc'd from the cache. If the page was alloc'd only, but unwritten, it will not appear on disk. Signed-off-by: -
David Howells authored
Add and document asynchronous operation handling for use by FS-Cache's data storage and retrieval routines. The following documentation is added to: Documentation/filesystems/caching/operations.txt ================================ ASYNCHRONOUS OPERATIONS HANDLING ================================ ======== OVERVIEW ======== FS-Cache has an asynchronous operations handling facility that it uses for its data storage and retrieval routines. Its operations are represented by fscache_operation structs, though these are usually embedded into some other structure. This facility is available to and expected to be be used by the cache backends, and FS-Cache will create operations and pass them off to the appropriate cache backend for completion. To make use of this facility, <linux/fscache-cache.h> should be #included. =============================== OPERATION RECORD INITIALISATION =============================== An operation is recorded in an fscache_operation struct: struct fscache_operation { union { struct work_struct fast_work; struct slow_work slow_work; }; unsigned long flags; fscache_operation_processor_t processor; ... }; Someone wanting to issue an operation should allocate something with this struct embedded in it. They should initialise it by calling: void fscache_operation_init(struct fscache_operation *op, fscache_operation_release_t release); with the operation to be initialised and the release function to use. The op->flags parameter should be set to indicate the CPU time provision and the exclusivity (see the Parameters section). The op->fast_work, op->slow_work and op->processor flags should be set as appropriate for the CPU time provision (see the Parameters section). FSCACHE_OP_WAITING may be set in op->flags prior to each submission of the operation and waited for afterwards. ========== PARAMETERS ========== There are a number of parameters that can be set in the operation record's flag parameter. There are three options for the provision of CPU time in these operations: (1) The operation may be done synchronously (FSCACHE_OP_MYTHREAD). A thread may decide it wants to handle an operation itself without deferring it to another thread. This is, for example, used in read operations for calling readpages() on the backing filesystem in CacheFiles. Although readpages() does an asynchronous data fetch, the determination of whether pages exist is done synchronously - and the netfs does not proceed until this has been determined. If this option is to be used, FSCACHE_OP_WAITING must be set in op->flags before submitting the operation, and the operating thread must wait for it to be cleared before proceeding: wait_on_bit(&op->flags, FSCACHE_OP_WAITING, fscache_wait_bit, TASK_UNINTERRUPTIBLE); (2) The operation may be fast asynchronous (FSCACHE_OP_FAST), in which case it will be given to keventd to process. Such an operation is not permitted to sleep on I/O. This is, for example, used by CacheFiles to copy data from a backing fs page to a netfs page after the backing fs has read the page in. If this option is used, op->fast_work and op->processor must be initialised before submitting the operation: INIT_WORK(&op->fast_work, do_some_work); (3) The operation may be slow asynchronous (FSCACHE_OP_SLOW), in which case it will be given to the slow work facility to process. Such an operation is permitted to sleep on I/O. This is, for example, used by FS-Cache to handle background writes of pages that have just been fetched from a remote server. If this option is used, op->slow_work and op->processor must be initialised before submitting the operation: fscache_operation_init_slow(op, processor) Furthermore, operations may be one of two types: (1) Exclusive (FSCACHE_OP_EXCLUSIVE). Operations of this type may not run in conjunction with any other operation on the object being operated upon. An example of this is the attribute change operation, in which the file being written to may need truncation. (2) Shareable. Operations of this type may be running simultaneously. It's up to the operation implementation to prevent interference between other operations running at the same time. ========= PROCEDURE ========= Operations are used through the following procedure: (1) The submitting thread must allocate the operation and initialise it itself. Normally this would be part of a more specific structure with the generic op embedded within. (2) The submitting thread must then submit the operation for processing using one of the following two functions: int fscache_submit_op(struct fscache_object *object, struct fscache_operation *op); int fscache_submit_exclusive_op(struct fscache_object *object, struct fscache_operation *op); The first function should be used to submit non-exclusive ops and the second to submit exclusive ones. The caller must still set the FSCACHE_OP_EXCLUSIVE flag. If successful, both functions will assign the operation to the specified object and return 0. -ENOBUFS will be returned if the object specified is permanently unavailable. The operation manager will defer operations on an object that is still undergoing lookup or creation. The operation will also be deferred if an operation of conflicting exclusivity is in progress on the object. If the operation is asynchronous, the manager will retain a reference to it, so the caller should put their reference to it by passing it to: void fscache_put_operation(struct fscache_operation *op); (3) If the submitting thread wants to do the work itself, and has marked the operation with FSCACHE_OP_MYTHREAD, then it should monitor FSCACHE_OP_WAITING as described above and check the state of the object if necessary (the object might have died whilst the thread was waiting). When it has finished doing its processing, it should call fscache_put_operation() on it. (4) The operation holds an effective lock upon the object, preventing other exclusive ops conflicting until it is released. The operation can be enqueued for further immediate asynchronous processing by adjusting the CPU time provisioning option if necessary, eg: op->flags &= ~FSCACHE_OP_TYPE; op->flags |= ~FSCACHE_OP_FAST; and calling: void fscache_enqueue_operation(struct fscache_operation *op) This can be used to allow other things to have use of the worker thread pools. ===================== ASYNCHRONOUS CALLBACK ===================== When used in asynchronous mode, the worker thread pool will invoke the processor method with a pointer to the operation. This should then get at the container struct by using container_of(): static void fscache_write_op(struct fscache_operation *_op) { struct fscache_storage *op = container_of(_op, struct fscache_storage, op); ... } The caller holds a reference on the operation, and will invoke fscache_put_operation() when the processor function returns. The processor function is at liberty to call fscache_enqueue_operation() or to take extra references. Signed-off-by: -
David Howells authored
Implement the cookie management part of the FS-Cache netfs client API. The documentation and API header file were added in a previous patch. This patch implements the following three functions: (1) fscache_acquire_cookie(). Acquire a cookie to represent an object to the netfs. If the object in question is a non-index object, then that object and its parent indices will be created on disk at this point if they don't already exist. Index creation is deferred because an index may reside in multiple caches. (2) fscache_relinquish_cookie(). Retire or release a cookie previously acquired. At this point, the object on disk may be destroyed. (3) fscache_update_cookie(). Update the in-cache representation of a cookie. This is used to update the auxiliary data for coherency management purposes. With this patch it is possible to have a netfs instruct a cache backend to look up, validate and create metadata on disk and to destroy it again. The ability to actually store and retrieve data in the objects so created is added in later patches. Note that these functions will never return an error. _All_ errors are handled internally to FS-Cache. The worst that can happen is that fscache_acquire_cookie() may return a NULL pointer - which is considered a negative cookie pointer and can be passed back to any function that takes a cookie without harm. A negative cookie pointer merely suppresses caching at that level. The stub in linux/fscache.h will detect inline the negative cookie pointer and abort the operation as fast as possible. This means that the compiler doesn't have to set up for a call in that case. See the documentation in Documentation/filesystems/caching/netfs-api.txt for more information. Signed-off-by: -
David Howells authored
Implement the cache object management state machine. The following documentation is added to illuminate the working of this state machine. It will also be added as: Documentation/filesystems/caching/object.txt ==================================================== IN-KERNEL CACHE OBJECT REPRESENTATION AND MANAGEMENT ==================================================== ============== REPRESENTATION ============== FS-Cache maintains an in-kernel representation of each object that a netfs is currently interested in. Such objects are represented by the fscache_cookie struct and are referred to as cookies. FS-Cache also maintains a separate in-kernel representation of the objects that a cache backend is currently actively caching. Such objects are represented by the fscache_object struct. The cache backends allocate these upon request, and are expected to embed them in their own representations. These are referred to as objects. There is a 1:N relationship between cookies and objects. A cookie may be represented by multiple objects - an index may exist in more than one cache - or even by no objects (it may not be cached). Furthermore, both cookies and objects are hierarchical. The two hierarchies correspond, but the cookies tree is a superset of the union of the object trees of multiple caches: NETFS INDEX TREE : CACHE 1 : CACHE 2 : : : +-----------+ : +----------->| IObject | : +-----------+ | : +-----------+ : | ICookie |-------+ : | : +-----------+ | : | : +-----------+ | +------------------------------>| IObject | | : | : +-----------+ | : V : | | : +-----------+ : | V +----------->| IObject | : | +-----------+ | : +-----------+ : | | ICookie |-------+ : | : V +-----------+ | : | : +-----------+ | +------------------------------>| IObject | +-----+-----+ : | : +-----------+ | | : | : | V | : V : | +-----------+ | : +-----------+ : | | ICookie |------------------------->| IObject | : | +-----------+ | : +-----------+ : | | V : | : V | +-----------+ : | : +-----------+ | | ICookie |-------------------------------->| IObject | | +-----------+ : | : +-----------+ V | : V : | +-----------+ | : +-----------+ : | | DCookie |------------------------->| DObject | : | +-----------+ | : +-----------+ : | | : : | +-------+-------+ : : | | | : : | V V : : V +-----------+ +-----------+ : : +-----------+ | DCookie | | DCookie |------------------------>| DObject | +-----------+ +-----------+ : : +-----------+ : : In the above illustration, ICookie and IObject represent indices and DCookie and DObject represent data storage objects. Indices may have representation in multiple caches, but currently, non-index objects may not. Objects of any type may also be entirely unrepresented. As far as the netfs API goes, the netfs is only actually permitted to see pointers to the cookies. The cookies themselves and any objects attached to those cookies are hidden from it. =============================== OBJECT MANAGEMENT STATE MACHINE =============================== Within FS-Cache, each active object is managed by its own individual state machine. The state for an object is kept in the fscache_object struct, in object->state. A cookie may point to a set of objects that are in different states. Each state has an action associated with it that is invoked when the machine wakes up in that state. There are four logical sets of states: (1) Preparation: states that wait for the parent objects to become ready. The representations are hierarchical, and it is expected that an object must be created or accessed with respect to its parent object. (2) Initialisation: states that perform lookups in the cache and validate what's found and that create on disk any missing metadata. (3) Normal running: states that allow netfs operations on objects to proceed and that update the state of objects. (4) Termination: states that detach objects from their netfs cookies, that delete objects from disk, that handle disk and system errors and that free up in-memory resources. In most cases, transitioning between states is in response to signalled events. When a state has finished processing, it will usually set the mask of events in which it is interested (object->event_mask) and relinquish the worker thread. Then when an event is raised (by calling fscache_raise_event()), if the event is not masked, the object will be queued for processing (by calling fscache_enqueue_object()). PROVISION OF CPU TIME --------------------- The work to be done by the various states is given CPU time by the threads of the slow work facility (see Documentation/slow-work.txt). This is used in preference to the workqueue facility because: (1) Threads may be completely occupied for very long periods of time by a particular work item. These state actions may be doing sequences of synchronous, journalled disk accesses (lookup, mkdir, create, setxattr, getxattr, truncate, unlink, rmdir, rename). (2) Threads may do little actual work, but may rather spend a lot of time sleeping on I/O. This means that single-threaded and 1-per-CPU-threaded workqueues don't necessarily have the right numbers of threads. LOCKING SIMPLIFICATION ---------------------- Because only one worker thread may be operating on any particular object's state machine at once, this simplifies the locking, particularly with respect to disconnecting the netfs's representation of a cache object (fscache_cookie) from the cache backend's representation (fscache_object) - which may be requested from either end. ================= THE SET OF STATES ================= The object state machine has a set of states that it can be in. There are preparation states in which the object sets itself up and waits for its parent object to transit to a state that allows access to its children: (1) State FSCACHE_OBJECT_INIT. Initialise the object and wait for the parent object to become active. In the cache, it is expected that it will not be possible to look an object up from the parent object, until that parent object itself has been looked up. There are initialisation states in which the object sets itself up and accesses disk for the object metadata: (2) State FSCACHE_OBJECT_LOOKING_UP. Look up the object on disk, using the parent as a starting point. FS-Cache expects the cache backend to probe the cache to see whether this object is represented there, and if it is, to see if it's valid (coherency management). The cache should call fscache_object_lookup_negative() to indicate lookup failure for whatever reason, and should call fscache_obtained_object() to indicate success. At the completion of lookup, FS-Cache will let the netfs go ahead with read operations, no matter whether the file is yet cached. If not yet cached, read operations will be immediately rejected with ENODATA until the first known page is uncached - as to that point there can be no data to be read out of the cache for that file that isn't currently also held in the pagecache. (3) State FSCACHE_OBJECT_CREATING. Create an object on disk, using the parent as a starting point. This happens if the lookup failed to find the object, or if the object's coherency data indicated what's on disk is out of date. In this state, FS-Cache expects the cache to create The cache should call fscache_obtained_object() if creation completes successfully, fscache_object_lookup_negative() otherwise. At the completion of creation, FS-Cache will start processing write operations the netfs has queued for an object. If creation failed, the write ops will be transparently discarded, and nothing recorded in the cache. There are some normal running states in which the object spends its time servicing netfs requests: (4) State FSCACHE_OBJECT_AVAILABLE. A transient state in which pending operations are started, child objects are permitted to advance from FSCACHE_OBJECT_INIT state, and temporary lookup data is freed. (5) State FSCACHE_OBJECT_ACTIVE. The normal running state. In this state, requests the netfs makes will be passed on to the cache. (6) State FSCACHE_OBJECT_UPDATING. The state machine comes here to update the object in the cache from the netfs's records. This involves updating the auxiliary data that is used to maintain coherency. And there are terminal states in which an object cleans itself up, deallocates memory and potentially deletes stuff from disk: (7) State FSCACHE_OBJECT_LC_DYING. The object comes here if it is dying because of a lookup or creation error. This would be due to a disk error or system error of some sort. Temporary data is cleaned up, and the parent is released. (8) State FSCACHE_OBJECT_DYING. The object comes here if it is dying due to an error, because its parent cookie has been relinquished by the netfs or because the cache is being withdrawn. Any child objects waiting on this one are given CPU time so that they too can destroy themselves. This object waits for all its children to go away before advancing to the next state. (9) State FSCACHE_OBJECT_ABORT_INIT. The object comes to this state if it was waiting on its parent in FSCACHE_OBJECT_INIT, but its parent died. The object will destroy itself so that the parent may proceed from the FSCACHE_OBJECT_DYING state. (10) State FSCACHE_OBJECT_RELEASING. (11) State FSCACHE_OBJECT_RECYCLING. The object comes to one of these two states when dying once it is rid of all its children, if it is dying because the netfs relinquished its cookie. In the first state, the cached data is expected to persist, and in the second it will be deleted. (12) State FSCACHE_OBJECT_WITHDRAWING. The object transits to this state if the cache decides it wants to withdraw the object from service, perhaps to make space, but also due to error or just because the whole cache is being withdrawn. (13) State FSCACHE_OBJECT_DEAD. The object transits to this state when the in-memory object record is ready to be deleted. The object processor shouldn't ever see an object in this state. THE SET OF EVENTS ----------------- There are a number of events that can be raised to an object state machine: (*) FSCACHE_OBJECT_EV_UPDATE The netfs requested that an object be updated. The state machine will ask the cache backend to update the object, and the cache backend will ask the netfs for details of the change through its cookie definition ops. (*) FSCACHE_OBJECT_EV_CLEARED This is signalled in two circumstances: (a) when an object's last child object is dropped and (b) when the last operation outstanding on an object is completed. This is used to proceed from the dying state. (*) FSCACHE_OBJECT_EV_ERROR This is signalled when an I/O error occurs during the processing of some object. (*) FSCACHE_OBJECT_EV_RELEASE (*) FSCACHE_OBJECT_EV_RETIRE These are signalled when the netfs relinquishes a cookie it was using. The event selected depends on whether the netfs asks for the backing object to be retired (deleted) or retained. (*) FSCACHE_OBJECT_EV_WITHDRAW This is signalled when the cache backend wants to withdraw an object. This means that the object will have to be detached from the netfs's cookie. Because the withdrawing releasing/retiring events are all handled by the object state machine, it doesn't matter if there's a collision with both ends trying to sever the connection at the same time. The state machine can just pick which one it wants to honour, and that effects the other. Signed-off-by:
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