diff options
Diffstat (limited to 'Documentation/filesystems')
| -rw-r--r-- | Documentation/filesystems/ext2.rst | 1 | ||||
| -rw-r--r-- | Documentation/filesystems/f2fs.rst | 36 | ||||
| -rw-r--r-- | Documentation/filesystems/files.rst | 8 | ||||
| -rw-r--r-- | Documentation/filesystems/nfs/exporting.rst | 52 | ||||
| -rw-r--r-- | Documentation/filesystems/overlayfs.rst | 36 | ||||
| -rw-r--r-- | Documentation/filesystems/proc.rst | 2 |
6 files changed, 123 insertions, 12 deletions
diff --git a/Documentation/filesystems/ext2.rst b/Documentation/filesystems/ext2.rst index d83dbbb162e2..c2fce22cfd03 100644 --- a/Documentation/filesystems/ext2.rst +++ b/Documentation/filesystems/ext2.rst @@ -1,6 +1,7 @@ .. SPDX-License-Identifier: GPL-2.0 +============================== The Second Extended Filesystem ============================== diff --git a/Documentation/filesystems/f2fs.rst b/Documentation/filesystems/f2fs.rst index b8ee761c9922..dae15c96e659 100644 --- a/Documentation/filesystems/f2fs.rst +++ b/Documentation/filesystems/f2fs.rst @@ -260,6 +260,14 @@ compress_extension=%s Support adding specified extension, so that f2fs can enab For other files, we can still enable compression via ioctl. Note that, there is one reserved special extension '*', it can be set to enable compression for all files. +compress_chksum Support verifying chksum of raw data in compressed cluster. +compress_mode=%s Control file compression mode. This supports "fs" and "user" + modes. In "fs" mode (default), f2fs does automatic compression + on the compression enabled files. In "user" mode, f2fs disables + the automaic compression and gives the user discretion of + choosing the target file and the timing. The user can do manual + compression/decompression on the compression enabled files using + ioctls. inlinecrypt When possible, encrypt/decrypt the contents of encrypted files using the blk-crypto framework rather than filesystem-layer encryption. This allows the use of @@ -810,6 +818,34 @@ Compress metadata layout:: | data length | data chksum | reserved | compressed data | +-------------+-------------+----------+----------------------------+ +Compression mode +-------------------------- + +f2fs supports "fs" and "user" compression modes with "compression_mode" mount option. +With this option, f2fs provides a choice to select the way how to compress the +compression enabled files (refer to "Compression implementation" section for how to +enable compression on a regular inode). + +1) compress_mode=fs +This is the default option. f2fs does automatic compression in the writeback of the +compression enabled files. + +2) compress_mode=user +This disables the automaic compression and gives the user discretion of choosing the +target file and the timing. The user can do manual compression/decompression on the +compression enabled files using F2FS_IOC_DECOMPRESS_FILE and F2FS_IOC_COMPRESS_FILE +ioctls like the below. + +To decompress a file, + +fd = open(filename, O_WRONLY, 0); +ret = ioctl(fd, F2FS_IOC_DECOMPRESS_FILE); + +To compress a file, + +fd = open(filename, O_WRONLY, 0); +ret = ioctl(fd, F2FS_IOC_COMPRESS_FILE); + NVMe Zoned Namespace devices ---------------------------- diff --git a/Documentation/filesystems/files.rst b/Documentation/filesystems/files.rst index cbf8e57376bf..bcf84459917f 100644 --- a/Documentation/filesystems/files.rst +++ b/Documentation/filesystems/files.rst @@ -62,7 +62,7 @@ the fdtable structure - be held. 4. To look up the file structure given an fd, a reader - must use either fcheck() or fcheck_files() APIs. These + must use either lookup_fd_rcu() or files_lookup_fd_rcu() APIs. These take care of barrier requirements due to lock-free lookup. An example:: @@ -70,7 +70,7 @@ the fdtable structure - struct file *file; rcu_read_lock(); - file = fcheck(fd); + file = lookup_fd_rcu(fd); if (file) { ... } @@ -84,7 +84,7 @@ the fdtable structure - on ->f_count:: rcu_read_lock(); - file = fcheck_files(files, fd); + file = files_lookup_fd_rcu(files, fd); if (file) { if (atomic_long_inc_not_zero(&file->f_count)) *fput_needed = 1; @@ -104,7 +104,7 @@ the fdtable structure - lock-free, they must be installed using rcu_assign_pointer() API. If they are looked up lock-free, rcu_dereference() must be used. However it is advisable to use files_fdtable() - and fcheck()/fcheck_files() which take care of these issues. + and lookup_fd_rcu()/files_lookup_fd_rcu() which take care of these issues. 7. While updating, the fdtable pointer must be looked up while holding files->file_lock. If ->file_lock is dropped, then diff --git a/Documentation/filesystems/nfs/exporting.rst b/Documentation/filesystems/nfs/exporting.rst index 33d588a01ace..0e98edd353b5 100644 --- a/Documentation/filesystems/nfs/exporting.rst +++ b/Documentation/filesystems/nfs/exporting.rst @@ -154,6 +154,11 @@ struct which has the following members: to find potential names, and matches inode numbers to find the correct match. + flags + Some filesystems may need to be handled differently than others. The + export_operations struct also includes a flags field that allows the + filesystem to communicate such information to nfsd. See the Export + Operations Flags section below for more explanation. A filehandle fragment consists of an array of 1 or more 4byte words, together with a one byte "type". @@ -163,3 +168,50 @@ generated by encode_fh, in which case it will have been padded with nuls. Rather, the encode_fh routine should choose a "type" which indicates the decode_fh how much of the filehandle is valid, and how it should be interpreted. + +Export Operations Flags +----------------------- +In addition to the operation vector pointers, struct export_operations also +contains a "flags" field that allows the filesystem to communicate to nfsd +that it may want to do things differently when dealing with it. The +following flags are defined: + + EXPORT_OP_NOWCC - disable NFSv3 WCC attributes on this filesystem + RFC 1813 recommends that servers always send weak cache consistency + (WCC) data to the client after each operation. The server should + atomically collect attributes about the inode, do an operation on it, + and then collect the attributes afterward. This allows the client to + skip issuing GETATTRs in some situations but means that the server + is calling vfs_getattr for almost all RPCs. On some filesystems + (particularly those that are clustered or networked) this is expensive + and atomicity is difficult to guarantee. This flag indicates to nfsd + that it should skip providing WCC attributes to the client in NFSv3 + replies when doing operations on this filesystem. Consider enabling + this on filesystems that have an expensive ->getattr inode operation, + or when atomicity between pre and post operation attribute collection + is impossible to guarantee. + + EXPORT_OP_NOSUBTREECHK - disallow subtree checking on this fs + Many NFS operations deal with filehandles, which the server must then + vet to ensure that they live inside of an exported tree. When the + export consists of an entire filesystem, this is trivial. nfsd can just + ensure that the filehandle live on the filesystem. When only part of a + filesystem is exported however, then nfsd must walk the ancestors of the + inode to ensure that it's within an exported subtree. This is an + expensive operation and not all filesystems can support it properly. + This flag exempts the filesystem from subtree checking and causes + exportfs to get back an error if it tries to enable subtree checking + on it. + + EXPORT_OP_CLOSE_BEFORE_UNLINK - always close cached files before unlinking + On some exportable filesystems (such as NFS) unlinking a file that + is still open can cause a fair bit of extra work. For instance, + the NFS client will do a "sillyrename" to ensure that the file + sticks around while it's still open. When reexporting, that open + file is held by nfsd so we usually end up doing a sillyrename, and + then immediately deleting the sillyrenamed file just afterward when + the link count actually goes to zero. Sometimes this delete can race + with other operations (for instance an rmdir of the parent directory). + This flag causes nfsd to close any open files for this inode _before_ + calling into the vfs to do an unlink or a rename that would replace + an existing file. diff --git a/Documentation/filesystems/overlayfs.rst b/Documentation/filesystems/overlayfs.rst index 580ab9a0fe31..587a93973929 100644 --- a/Documentation/filesystems/overlayfs.rst +++ b/Documentation/filesystems/overlayfs.rst @@ -97,11 +97,13 @@ directory trees to be in the same filesystem and there is no requirement that the root of a filesystem be given for either upper or lower. -The lower filesystem can be any filesystem supported by Linux and does -not need to be writable. The lower filesystem can even be another -overlayfs. The upper filesystem will normally be writable and if it -is it must support the creation of trusted.* extended attributes, and -must provide valid d_type in readdir responses, so NFS is not suitable. +A wide range of filesystems supported by Linux can be the lower filesystem, +but not all filesystems that are mountable by Linux have the features +needed for OverlayFS to work. The lower filesystem does not need to be +writable. The lower filesystem can even be another overlayfs. The upper +filesystem will normally be writable and if it is it must support the +creation of trusted.* and/or user.* extended attributes, and must provide +valid d_type in readdir responses, so NFS is not suitable. A read-only overlay of two read-only filesystems may use any filesystem type. @@ -467,14 +469,18 @@ summarized in the `Inode properties`_ table above. Changes to underlying filesystems --------------------------------- -Offline changes, when the overlay is not mounted, are allowed to either -the upper or the lower trees. - Changes to the underlying filesystems while part of a mounted overlay filesystem are not allowed. If the underlying filesystem is changed, the behavior of the overlay is undefined, though it will not result in a crash or deadlock. +Offline changes, when the overlay is not mounted, are allowed to the +upper tree. Offline changes to the lower tree are only allowed if the +"metadata only copy up", "inode index", and "redirect_dir" features +have not been used. If the lower tree is modified and any of these +features has been used, the behavior of the overlay is undefined, +though it will not result in a crash or deadlock. + When the overlay NFS export feature is enabled, overlay filesystems behavior on offline changes of the underlying lower layer is different than the behavior when NFS export is disabled. @@ -563,6 +569,11 @@ This verification may cause significant overhead in some cases. Note: the mount options index=off,nfs_export=on are conflicting for a read-write mount and will result in an error. +Note: the mount option uuid=off can be used to replace UUID of the underlying +filesystem in file handles with null, and effectively disable UUID checks. This +can be useful in case the underlying disk is copied and the UUID of this copy +is changed. This is only applicable if all lower/upper/work directories are on +the same filesystem, otherwise it will fallback to normal behaviour. Volatile mount -------------- @@ -583,6 +594,15 @@ fresh one. In very limited cases where the user knows that the system has not crashed and contents of upperdir are intact, The "volatile" directory can be removed. + +User xattr +---------- + +The the "-o userxattr" mount option forces overlayfs to use the +"user.overlay." xattr namespace instead of "trusted.overlay.". This is +useful for unprivileged mounting of overlayfs. + + Testsuite --------- diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst index e5fa972d4c76..2fa69f710e2a 100644 --- a/Documentation/filesystems/proc.rst +++ b/Documentation/filesystems/proc.rst @@ -210,6 +210,7 @@ read the file /proc/PID/status:: NoNewPrivs: 0 Seccomp: 0 Speculation_Store_Bypass: thread vulnerable + SpeculationIndirectBranch: conditional enabled voluntary_ctxt_switches: 0 nonvoluntary_ctxt_switches: 1 @@ -292,6 +293,7 @@ It's slow but very precise. NoNewPrivs no_new_privs, like prctl(PR_GET_NO_NEW_PRIV, ...) Seccomp seccomp mode, like prctl(PR_GET_SECCOMP, ...) Speculation_Store_Bypass speculative store bypass mitigation status + SpeculationIndirectBranch indirect branch speculation mode Cpus_allowed mask of CPUs on which this process may run Cpus_allowed_list Same as previous, but in "list format" Mems_allowed mask of memory nodes allowed to this process |