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* Merge branch 'hash' of git://ftp.sciencehorizons.net/linuxLinus Torvalds2016-05-281-26/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull string hash improvements from George Spelvin: "This series does several related things: - Makes the dcache hash (fs/namei.c) useful for general kernel use. (Thanks to Bruce for noticing the zero-length corner case) - Converts the string hashes in <linux/sunrpc/svcauth.h> to use the above. - Avoids 64-bit multiplies in hash_64() on 32-bit platforms. Two 32-bit multiplies will do well enough. - Rids the world of the bad hash multipliers in hash_32. This finishes the job started in commit 689de1d6ca95 ("Minimal fix-up of bad hashing behavior of hash_64()") The vast majority of Linux architectures have hardware support for 32x32-bit multiply and so derive no benefit from "simplified" multipliers. The few processors that do not (68000, h8/300 and some models of Microblaze) have arch-specific implementations added. Those patches are last in the series. - Overhauls the dcache hash mixing. The patch in commit 0fed3ac866ea ("namei: Improve hash mixing if CONFIG_DCACHE_WORD_ACCESS") was an off-the-cuff suggestion. Replaced with a much more careful design that's simultaneously faster and better. (My own invention, as there was noting suitable in the literature I could find. Comments welcome!) - Modify the hash_name() loop to skip the initial HASH_MIX(). This would let us salt the hash if we ever wanted to. - Sort out partial_name_hash(). The hash function is declared as using a long state, even though it's truncated to 32 bits at the end and the extra internal state contributes nothing to the result. And some callers do odd things: - fs/hfs/string.c only allocates 32 bits of state - fs/hfsplus/unicode.c uses it to hash 16-bit unicode symbols not bytes - Modify bytemask_from_count to handle inputs of 1..sizeof(long) rather than 0..sizeof(long)-1. This would simplify users other than full_name_hash" Special thanks to Bruce Fields for testing and finding bugs in v1. (I learned some humbling lessons about "obviously correct" code.) On the arch-specific front, the m68k assembly has been tested in a standalone test harness, I've been in contact with the Microblaze maintainers who mostly don't care, as the hardware multiplier is never omitted in real-world applications, and I haven't heard anything from the H8/300 world" * 'hash' of git://ftp.sciencehorizons.net/linux: h8300: Add <asm/hash.h> microblaze: Add <asm/hash.h> m68k: Add <asm/hash.h> <linux/hash.h>: Add support for architecture-specific functions fs/namei.c: Improve dcache hash function Eliminate bad hash multipliers from hash_32() and hash_64() Change hash_64() return value to 32 bits <linux/sunrpc/svcauth.h>: Define hash_str() in terms of hashlen_string() fs/namei.c: Add hashlen_string() function Pull out string hash to <linux/stringhash.h>
| * Pull out string hash to <linux/stringhash.h>George Spelvin2016-05-281-26/+1
| | | | | | | | | | | | | | | | ... so they can be used without the rest of <linux/dcache.h> The hashlen_* macros will make sense next patch. Signed-off-by: George Spelvin <linux@sciencehorizons.net>
* | Merge branch 'ovl-fixes' into for-linusAl Viro2016-05-171-0/+12
|\ \ | |/ | | | | | | | | Backmerge to resolve a conflict in ovl_lookup_real(); "ovl_lookup_real(): use lookup_one_len_unlocked()" instead, but it was too late in the cycle to rebase.
| * vfs: add vfs_select_inode() helperMiklos Szeredi2016-05-101-0/+12
| | | | | | | | | | Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Cc: <stable@vger.kernel.org> # v4.2+
* | parallel lookups machinery, part 4 (and last)Al Viro2016-05-021-2/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If we *do* run into an in-lookup match, we need to wait for it to cease being in-lookup. Fortunately, we do have unused space in in-lookup dentries - d_lru is never looked at until it stops being in-lookup. So we can stash a pointer to wait_queue_head from stack frame of the caller of ->lookup(). Some precautions are needed while waiting, but it's not that hard - we do hold a reference to dentry we are waiting for, so it can't go away. If it's found to be in-lookup the wait_queue_head is still alive and will remain so at least while ->d_lock is held. Moreover, the condition we are waiting for becomes true at the same point where everything on that wq gets woken up, so we can just add ourselves to the queue once. d_alloc_parallel() gets a pointer to wait_queue_head_t from its caller; lookup_slow() adjusted, d_add_ci() taught to use d_alloc_parallel() if the dentry passed to it happens to be in-lookup one (i.e. if it's been called from the parallel lookup). That's pretty much it - all that remains is to switch ->i_mutex to rwsem and have lookup_slow() take it shared. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | parallel lookups machinery, part 3Al Viro2016-05-021-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We will need to be able to check if there is an in-lookup dentry with matching parent/name. Right now it's impossible, but as soon as start locking directories shared such beasts will appear. Add a secondary hash for locating those. Hash chains go through the same space where d_alias will be once it's not in-lookup anymore. Search is done under the same bitlock we use for modifications - with the primary hash we can rely on d_rehash() into the wrong chain being the worst that could happen, but here the pointers are buggered once it's removed from the chain. On the other hand, the chains are not going to be long and normally we'll end up adding to the chain anyway. That allows us to avoid bothering with ->d_lock when doing the comparisons - everything is stable until removed from chain. New helper: d_alloc_parallel(). Right now it allocates, verifies that no hashed and in-lookup matches exist and adds to in-lookup hash. Returns ERR_PTR() for error, hashed match (in the unlikely case it's been found) or new dentry. In-lookup matches trigger BUG() for now; that will change in the next commit when we introduce waiting for ongoing lookup to finish. Note that in-lookup matches won't be possible until we actually go for shared locking. lookup_slow() switched to use of d_alloc_parallel(). Again, these commits are separated only for making it easier to review. All this machinery will start doing something useful only when we go for shared locking; it's just that the combination is too large for my taste. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | beginning of transition to parallel lookups - marking in-lookup dentriesAl Viro2016-05-021-0/+18
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | marked as such when (would be) parallel lookup is about to pass them to actual ->lookup(); unmarked when * __d_add() is about to make it hashed, positive or not. * __d_move() (from d_splice_alias(), directly or via __d_unalias()) puts a preexisting dentry in its place * in caller of ->lookup() if it has escaped all of the above. Bug (WARN_ON, actually) if it reaches the final dput() or d_instantiate() while still marked such. As the result, we are guaranteed that for as long as the flag is set, dentry will * remain negative unhashed with positive refcount * never have its ->d_alias looked at * never have its ->d_lru looked at * never have its ->d_parent and ->d_name changed Right now we have at most one such for any given parent directory. With parallel lookups that restriction will weaken to * only exist when parent is locked shared * at most one with given (parent,name) pair (comparison of names is according to ->d_compare()) * only exist when there's no hashed dentry with the same (parent,name) Transition will take the next several commits; unfortunately, we'll only be able to switch to rwsem at the end of this series. The reason for not making it a single patch is to simplify review. New primitives: d_in_lookup() (a predicate checking if dentry is in the in-lookup state) and d_lookup_done() (tells the system that we are done with lookup and if it's still marked as in-lookup, it should cease to be such). Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* fs: add file_dentry()Miklos Szeredi2016-03-261-0/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This series fixes bugs in nfs and ext4 due to 4bacc9c9234c ("overlayfs: Make f_path always point to the overlay and f_inode to the underlay"). Regular files opened on overlayfs will result in the file being opened on the underlying filesystem, while f_path points to the overlayfs mount/dentry. This confuses filesystems which get the dentry from struct file and assume it's theirs. Add a new helper, file_dentry() [*], to get the filesystem's own dentry from the file. This checks file->f_path.dentry->d_flags against DCACHE_OP_REAL, and returns file->f_path.dentry if DCACHE_OP_REAL is not set (this is the common, non-overlayfs case). In the uncommon case it will call into overlayfs's ->d_real() to get the underlying dentry, matching file_inode(file). The reason we need to check against the inode is that if the file is copied up while being open, d_real() would return the upper dentry, while the open file comes from the lower dentry. [*] If possible, it's better simply to use file_inode() instead. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Tested-by: Goldwyn Rodrigues <rgoldwyn@suse.com> Reviewed-by: Trond Myklebust <trond.myklebust@primarydata.com> Cc: <stable@vger.kernel.org> # v4.2 Cc: David Howells <dhowells@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Daniel Axtens <dja@axtens.net>
* Merge tag 'for-f2fs-4.6' of ↵Linus Torvalds2016-03-211-0/+2
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs Pull f2fs updates from Jaegeuk Kim: "New Features: - uplift filesystem encryption into fs/crypto/ - give sysfs entries to control memroy consumption Enhancements: - aio performance by preallocating blocks in ->write_iter - use writepages lock for only WB_SYNC_ALL - avoid redundant inline_data conversion - enhance forground GC - use wait_for_stable_page as possible - speed up SEEK_DATA and fiiemap Bug Fixes: - corner case in terms of -ENOSPC for inline_data - hung task caused by long latency in shrinker - corruption between atomic write and f2fs_trace_pid - avoid garbage lengths in dentries - revoke atomicly written pages if an error occurs In addition, there are various minor bug fixes and clean-ups" * tag 'for-f2fs-4.6' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs: (81 commits) f2fs: submit node page write bios when really required f2fs: add missing argument to f2fs_setxattr stub f2fs: fix to avoid unneeded unlock_new_inode f2fs: clean up opened code with f2fs_update_dentry f2fs: declare static functions f2fs: use cryptoapi crc32 functions f2fs: modify the readahead method in ra_node_page() f2fs crypto: sync ext4_lookup and ext4_file_open fs crypto: move per-file encryption from f2fs tree to fs/crypto f2fs: mutex can't be used by down_write_nest_lock() f2fs: recovery missing dot dentries in root directory f2fs: fix to avoid deadlock when merging inline data f2fs: introduce f2fs_flush_merged_bios for cleanup f2fs: introduce f2fs_update_data_blkaddr for cleanup f2fs crypto: fix incorrect positioning for GCing encrypted data page f2fs: fix incorrect upper bound when iterating inode mapping tree f2fs: avoid hungtask problem caused by losing wake_up f2fs: trace old block address for CoWed page f2fs: try to flush inode after merging inline data f2fs: show more info about superblock recovery ...
| * fs crypto: move per-file encryption from f2fs tree to fs/cryptoJaegeuk Kim2016-03-171-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch adds the renamed functions moved from the f2fs crypto files. 1. definitions for per-file encryption used by ext4 and f2fs. 2. crypto.c for encrypt/decrypt functions a. IO preparation: - fscrypt_get_ctx / fscrypt_release_ctx b. before IOs: - fscrypt_encrypt_page - fscrypt_decrypt_page - fscrypt_zeroout_range c. after IOs: - fscrypt_decrypt_bio_pages - fscrypt_pullback_bio_page - fscrypt_restore_control_page 3. policy.c supporting context management. a. For ioctls: - fscrypt_process_policy - fscrypt_get_policy b. For context permission - fscrypt_has_permitted_context - fscrypt_inherit_context 4. keyinfo.c to handle permissions - fscrypt_get_encryption_info - fscrypt_free_encryption_info 5. fname.c to support filename encryption a. general wrapper functions - fscrypt_fname_disk_to_usr - fscrypt_fname_usr_to_disk - fscrypt_setup_filename - fscrypt_free_filename b. specific filename handling functions - fscrypt_fname_alloc_buffer - fscrypt_fname_free_buffer 6. Makefile and Kconfig Cc: Al Viro <viro@ftp.linux.org.uk> Signed-off-by: Michael Halcrow <mhalcrow@google.com> Signed-off-by: Ildar Muslukhov <ildarm@google.com> Signed-off-by: Uday Savagaonkar <savagaon@google.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
* | uninline d_add()Al Viro2016-03-141-14/+1
| | | | | | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | replace d_add_unique() with saner primitiveAl Viro2016-03-141-17/+1
| | | | | | | | | | | | | | | | | | new primitive: d_exact_alias(dentry, inode). If there is an unhashed dentry with the same name/parent and given inode, rehash, grab and return it. Otherwise, return NULL. The only caller of d_add_unique() switched to d_exact_alias() + d_splice_alias(). Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | use ->d_seq to get coherency between ->d_inode and ->d_flagsAl Viro2016-02-291-3/+1
|/ | | | | | | | | | Games with ordering and barriers are way too brittle. Just bump ->d_seq before and after updating ->d_inode and ->d_flags type bits, so that verifying ->d_seq would guarantee they are coherent. Cc: stable@vger.kernel.org # v3.13+ Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* include/linux/dcache.h: remove semicolons from HASH_LEN_DECLAREAndrew Morton2016-01-141-2/+2
| | | | | | | | | A little cleanup - the invocation site provdes the semicolon. Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Al Viro <viro@ZenIV.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* include, lib: add __printf attributes to several function prototypesNicolas Iooss2015-07-171-1/+2
| | | | | | | | | | | | | | | | | | | | | | Using __printf attributes helps to detect several format string issues at compile time (even though -Wformat-security is currently disabled in Makefile). For example it can detect when formatting a pointer as a number, like the issue fixed in commit a3fa71c40f18 ("wl18xx: show rx_frames_per_rates as an array as it really is"), or when the arguments do not match the format string, c.f. for example commit 5ce1aca81435 ("reiserfs: fix __RASSERT format string"). To prevent similar bugs in the future, add a __printf attribute to every function prototype which needs one in include/linux/ and lib/. These functions were mostly found by using gcc's -Wsuggest-attribute=format flag. Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@m4x.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Felipe Balbi <balbi@ti.com> Cc: Joel Becker <jlbec@evilplan.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* make simple_positive() publicAl Viro2015-06-231-0/+5
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* overlayfs: Make f_path always point to the overlay and f_inode to the underlayDavid Howells2015-06-191-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Make file->f_path always point to the overlay dentry so that the path in /proc/pid/fd is correct and to ensure that label-based LSMs have access to the overlay as well as the underlay (path-based LSMs probably don't need it). Using my union testsuite to set things up, before the patch I see: [root@andromeda union-testsuite]# bash 5</mnt/a/foo107 [root@andromeda union-testsuite]# ls -l /proc/$$/fd/ ... lr-x------. 1 root root 64 Jun 5 14:38 5 -> /a/foo107 [root@andromeda union-testsuite]# stat /mnt/a/foo107 ... Device: 23h/35d Inode: 13381 Links: 1 ... [root@andromeda union-testsuite]# stat -L /proc/$$/fd/5 ... Device: 23h/35d Inode: 13381 Links: 1 ... After the patch: [root@andromeda union-testsuite]# bash 5</mnt/a/foo107 [root@andromeda union-testsuite]# ls -l /proc/$$/fd/ ... lr-x------. 1 root root 64 Jun 5 14:22 5 -> /mnt/a/foo107 [root@andromeda union-testsuite]# stat /mnt/a/foo107 ... Device: 23h/35d Inode: 40346 Links: 1 ... [root@andromeda union-testsuite]# stat -L /proc/$$/fd/5 ... Device: 23h/35d Inode: 40346 Links: 1 ... Note the change in where /proc/$$/fd/5 points to in the ls command. It was pointing to /a/foo107 (which doesn't exist) and now points to /mnt/a/foo107 (which is correct). The inode accessed, however, is the lower layer. The union layer is on device 25h/37d and the upper layer on 24h/36d. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* VFS: Impose ordering on accesses of d_inode and d_flagsDavid Howells2015-04-151-18/+3
| | | | | | | | | | | | | | | | | | | | | | | | Impose ordering on accesses of d_inode and d_flags to avoid the need to do this: if (!dentry->d_inode || d_is_negative(dentry)) { when this: if (d_is_negative(dentry)) { should suffice. This check is especially problematic if a dentry can have its type field set to something other than DENTRY_MISS_TYPE when d_inode is NULL (as in unionmount). What we really need to do is stick a write barrier between setting d_inode and setting d_flags and a read barrier between reading d_flags and reading d_inode. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* VFS: Add owner-filesystem positive/negative dentry checksDavid Howells2015-04-151-0/+38
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | Supply two functions to test whether a filesystem's own dentries are positive or negative (d_really_is_positive() and d_really_is_negative()). The problem is that the DCACHE_ENTRY_TYPE field of dentry->d_flags may be overridden by the union part of a layered filesystem and isn't thus necessarily indicative of the type of dentry. Normally, this would involve a negative dentry (ie. ->d_inode == NULL) having ->d_layer.lower pointed to a lower layer dentry, DCACHE_PINNING_LOWER set and the DCACHE_ENTRY_TYPE field set to something other than DCACHE_MISS_TYPE - but it could also involve, say, a DCACHE_SPECIAL_TYPE being overridden to DCACHE_WHITEOUT_TYPE if a 0,0 chardev is detected in the top layer. However, inside a filesystem, when that fs is looking at its own dentries, it probably wants to know if they are really negative or not - and doesn't care about the fallthrough bits used by the union. To this end, a filesystem should normally use d_really_is_positive/negative() when looking at its own dentries rather than d_is_positive/negative() and should use d_inode() to get at the inode. Anyone looking at someone else's dentries (this includes pathwalk) should use d_is_xxx() and d_backing_inode(). Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* VFS: Split DCACHE_FILE_TYPE into regular and special typesDavid Howells2015-02-221-3/+14
| | | | | | | | | | | | | | | Split DCACHE_FILE_TYPE into DCACHE_REGULAR_TYPE (dentries representing regular files) and DCACHE_SPECIAL_TYPE (representing blockdev, chardev, FIFO and socket files). d_is_reg() and d_is_special() are added to detect these subtypes and d_is_file() is left as the union of the two. This allows a number of places that use S_ISREG(dentry->d_inode->i_mode) to use d_is_reg(dentry) instead. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* VFS: Add a fallthrough flag for marking virtual dentriesDavid Howells2015-02-221-0/+9
| | | | | | | | | | | | | Add a DCACHE_FALLTHRU flag to indicate that, in a layered filesystem, this is a virtual dentry that covers another one in a lower layer that should be used instead. This may be recorded on medium if directory integration is stored there. The flag can be set with d_set_fallthru() and tested with d_is_fallthru(). Original-author: Valerie Aurora <vaurora@redhat.com> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* VFS: Add a whiteout dentry typeDavid Howells2015-02-221-6/+18
| | | | | | | | | | Add DCACHE_WHITEOUT_TYPE and provide a d_is_whiteout() accessor function. A d_is_miss() accessor is also added for ordinary cache misses and d_is_negative() is modified to indicate either an ordinary miss or an enforced miss (whiteout). Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* VFS: Introduce inode-getting helpers for layered/unioned fs environmentsDavid Howells2015-02-221-0/+57
| | | | | | | | | | | | | | | | Introduce some function for getting the inode (and also the dentry) in an environment where layered/unioned filesystems are in operation. The problem is that we have places where we need *both* the union dentry and the lower source or workspace inode or dentry available, but we can only have a handle on one of them. Therefore we need to derive the handle to the other from that. The idea is to introduce an extra field in struct dentry that allows the union dentry to refer to and pin the lower dentry. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* kill d_validate()Al Viro2015-01-251-3/+0
| | | | | | no users left Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* switch d_materialise_unique() users to d_splice_alias()Al Viro2014-11-191-1/+0
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* merge d_materialise_unique() into d_splice_alias()Al Viro2014-11-191-1/+1
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* move d_rcu from overlapping d_child to overlapping d_aliasAl Viro2014-11-031-4/+4
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* don't need that forward declaration of struct nameidata in dcache.h anymoreAl Viro2014-10-121-1/+0
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* take dname_external() into fs/dcache.cAl Viro2014-10-121-5/+0
| | | | | | | never used outside and it's too low-level for legitimate uses outside of fs/dcache.c anyway Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* vfs: Make d_invalidate return voidEric W. Biederman2014-10-091-1/+1
| | | | | | | | | | Now that d_invalidate can no longer fail, stop returning a useless return code. For the few callers that checked the return code update remove the handling of d_invalidate failure. Reviewed-by: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* vfs: Merge check_submounts_and_drop and d_invalidateEric W. Biederman2014-10-091-1/+0
| | | | | | | | | Now that d_invalidate is the only caller of check_submounts_and_drop, expand check_submounts_and_drop inline in d_invalidate. Reviewed-by: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* vfs: avoid non-forwarding large load after small store in path lookupLinus Torvalds2014-09-141-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | The performance regression that Josef Bacik reported in the pathname lookup (see commit 99d263d4c5b2 "vfs: fix bad hashing of dentries") made me look at performance stability of the dcache code, just to verify that the problem was actually fixed. That turned up a few other problems in this area. There are a few cases where we exit RCU lookup mode and go to the slow serializing case when we shouldn't, Al has fixed those and they'll come in with the next VFS pull. But my performance verification also shows that link_path_walk() turns out to have a very unfortunate 32-bit store of the length and hash of the name we look up, followed by a 64-bit read of the combined hash_len field. That screws up the processor store to load forwarding, causing an unnecessary hickup in this critical routine. It's caused by the ugly calling convention for the "hash_name()" function, and easily fixed by just making hash_name() fill in the whole 'struct qstr' rather than passing it a pointer to just the hash value. With that, the profile for this function looks much smoother. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* dcache: d_obtain_alias callers don't all want DISCONNECTEDJ. Bruce Fields2014-08-071-0/+1
| | | | | | | | | | | | | | | | | | | | | There are a few d_obtain_alias callers that are using it to get the root of a filesystem which may already have an alias somewhere else. This is not the same as the filehandle-lookup case, and none of them actually need DCACHE_DISCONNECTED set. It isn't really a serious problem, but it would really be clearer if we reserved DCACHE_DISCONNECTED for those cases where it's actually needed. In the btrfs case this was causing a spurious printk from nfsd/nfsfh.c:fh_verify when it found an unexpected DCACHE_DISCONNECTED dentry. Josef worked around this by unsetting DCACHE_DISCONNECTED manually in 3a0dfa6a12e "Btrfs: unset DCACHE_DISCONNECTED when mounting default subvol", and this replaces that workaround. Cc: Josef Bacik <jbacik@fb.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* dentry_kill(): don't try to remove from shrink listAl Viro2014-05-011-0/+2
| | | | | | | | | | | | | | | | | | | If the victim in on the shrink list, don't remove it from there. If shrink_dentry_list() manages to remove it from the list before we are done - fine, we'll just free it as usual. If not - mark it with new flag (DCACHE_MAY_FREE) and leave it there. Eventually, shrink_dentry_list() will get to it, remove the sucker from shrink list and call dentry_kill(dentry, 0). Which is where we'll deal with freeing. Since now dentry_kill(dentry, 0) may happen after or during dentry_kill(dentry, 1), we need to recognize that (by seeing DCACHE_DENTRY_KILLED already set), unlock everything and either free the sucker (in case DCACHE_MAY_FREE has been set) or leave it for ongoing dentry_kill(dentry, 1) to deal with. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* vfs: add cross-renameMiklos Szeredi2014-04-011-0/+1
| | | | | | | | | | If flags contain RENAME_EXCHANGE then exchange source and destination files. There's no restriction on the type of the files; e.g. a directory can be exchanged with a symlink. Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: J. Bruce Fields <bfields@redhat.com>
* vfs: add d_is_dir()Miklos Szeredi2014-04-011-1/+6
| | | | | | | | | Add d_is_dir(dentry) helper which is analogous to S_ISDIR(). To avoid confusion, rename d_is_directory() to d_can_lookup(). Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Reviewed-by: J. Bruce Fields <bfields@redhat.com>
* dcache: allow word-at-a-time name hashing with big-endian CPUsWill Deacon2013-12-121-0/+2
| | | | | | | | | | | | | | | | When explicitly hashing the end of a string with the word-at-a-time interface, we have to be careful which end of the word we pick up. On big-endian CPUs, the upper-bits will contain the data we're after, so ensure we generate our masks accordingly (and avoid hashing whatever random junk may have been sitting after the string). This patch adds a new dcache helper, bytemask_from_count, which creates a mask appropriate for the CPU endianness. Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* VFS: Put a small type field into struct dentry::d_flagsDavid Howells2013-11-091-20/+83
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Put a type field into struct dentry::d_flags to indicate if the dentry is one of the following types that relate particularly to pathwalk: Miss (negative dentry) Directory "Automount" directory (defective - no i_op->lookup()) Symlink Other (regular, socket, fifo, device) The type field is set to one of the first five types on a dentry by calls to __d_instantiate() and d_obtain_alias() from information in the inode (if one is given). The type is cleared by dentry_unlink_inode() when it reconstitutes an existing dentry as a negative dentry. Accessors provided are: d_set_type(dentry, type) d_is_directory(dentry) d_is_autodir(dentry) d_is_symlink(dentry) d_is_file(dentry) d_is_negative(dentry) d_is_positive(dentry) A bunch of checks in pathname resolution switched to those. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* vfs: introduce d_instantiate_no_diralias()Miklos Szeredi2013-10-241-0/+1
| | | | | | | | | | ...which just returns -EBUSY if a directory alias would be created. This is to be used by fuse mkdir to make sure that a buggy or malicious userspace filesystem doesn't do anything nasty. Previously fuse used a private mutex for this purpose, which can now go away. Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
* super: fix calculation of shrinkable objects for small numbersGlauber Costa2013-09-101-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The sysctl knob sysctl_vfs_cache_pressure is used to determine which percentage of the shrinkable objects in our cache we should actively try to shrink. It works great in situations in which we have many objects (at least more than 100), because the aproximation errors will be negligible. But if this is not the case, specially when total_objects < 100, we may end up concluding that we have no objects at all (total / 100 = 0, if total < 100). This is certainly not the biggest killer in the world, but may matter in very low kernel memory situations. Signed-off-by: Glauber Costa <glommer@openvz.org> Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Mel Gorman <mgorman@suse.de> Cc: Dave Chinner <david@fromorbit.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Artem Bityutskiy <artem.bityutskiy@linux.intel.com> Cc: Arve Hjønnevåg <arve@android.com> Cc: Carlos Maiolino <cmaiolino@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Chuck Lever <chuck.lever@oracle.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: David Rientjes <rientjes@google.com> Cc: Gleb Natapov <gleb@redhat.com> Cc: Greg Thelen <gthelen@google.com> Cc: J. Bruce Fields <bfields@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: Jerome Glisse <jglisse@redhat.com> Cc: John Stultz <john.stultz@linaro.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Kent Overstreet <koverstreet@google.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Thomas Hellstrom <thellstrom@vmware.com> Cc: Trond Myklebust <Trond.Myklebust@netapp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* fs: bump inode and dentry counters to longGlauber Costa2013-09-101-5/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This series reworks our current object cache shrinking infrastructure in two main ways: * Noticing that a lot of users copy and paste their own version of LRU lists for objects, we put some effort in providing a generic version. It is modeled after the filesystem users: dentries, inodes, and xfs (for various tasks), but we expect that other users could benefit in the near future with little or no modification. Let us know if you have any issues. * The underlying list_lru being proposed automatically and transparently keeps the elements in per-node lists, and is able to manipulate the node lists individually. Given this infrastructure, we are able to modify the up-to-now hammer called shrink_slab to proceed with node-reclaim instead of always searching memory from all over like it has been doing. Per-node lru lists are also expected to lead to less contention in the lru locks on multi-node scans, since we are now no longer fighting for a global lock. The locks usually disappear from the profilers with this change. Although we have no official benchmarks for this version - be our guest to independently evaluate this - earlier versions of this series were performance tested (details at http://permalink.gmane.org/gmane.linux.kernel.mm/100537) yielding no visible performance regressions while yielding a better qualitative behavior in NUMA machines. With this infrastructure in place, we can use the list_lru entry point to provide memcg isolation and per-memcg targeted reclaim. Historically, those two pieces of work have been posted together. This version presents only the infrastructure work, deferring the memcg work for a later time, so we can focus on getting this part tested. You can see more about the history of such work at http://lwn.net/Articles/552769/ Dave Chinner (18): dcache: convert dentry_stat.nr_unused to per-cpu counters dentry: move to per-sb LRU locks dcache: remove dentries from LRU before putting on dispose list mm: new shrinker API shrinker: convert superblock shrinkers to new API list: add a new LRU list type inode: convert inode lru list to generic lru list code. dcache: convert to use new lru list infrastructure list_lru: per-node list infrastructure shrinker: add node awareness fs: convert inode and dentry shrinking to be node aware xfs: convert buftarg LRU to generic code xfs: rework buffer dispose list tracking xfs: convert dquot cache lru to list_lru fs: convert fs shrinkers to new scan/count API drivers: convert shrinkers to new count/scan API shrinker: convert remaining shrinkers to count/scan API shrinker: Kill old ->shrink API. Glauber Costa (7): fs: bump inode and dentry counters to long super: fix calculation of shrinkable objects for small numbers list_lru: per-node API vmscan: per-node deferred work i915: bail out earlier when shrinker cannot acquire mutex hugepage: convert huge zero page shrinker to new shrinker API list_lru: dynamically adjust node arrays This patch: There are situations in very large machines in which we can have a large quantity of dirty inodes, unused dentries, etc. This is particularly true when umounting a filesystem, where eventually since every live object will eventually be discarded. Dave Chinner reported a problem with this while experimenting with the shrinker revamp patchset. So we believe it is time for a change. This patch just moves int to longs. Machines where it matters should have a big long anyway. Signed-off-by: Glauber Costa <glommer@openvz.org> Cc: Dave Chinner <dchinner@redhat.com> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Artem Bityutskiy <artem.bityutskiy@linux.intel.com> Cc: Arve Hjønnevåg <arve@android.com> Cc: Carlos Maiolino <cmaiolino@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Chuck Lever <chuck.lever@oracle.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Dave Chinner <dchinner@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Gleb Natapov <gleb@redhat.com> Cc: Greg Thelen <gthelen@google.com> Cc: J. Bruce Fields <bfields@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: Jerome Glisse <jglisse@redhat.com> Cc: John Stultz <john.stultz@linaro.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Kent Overstreet <koverstreet@google.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Thomas Hellstrom <thellstrom@vmware.com> Cc: Trond Myklebust <Trond.Myklebust@netapp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* vfs: reorganize dput() memory accessesLinus Torvalds2013-09-081-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This is me being a bit OCD after all the dentry optimization work this merge window: profiles end up showing 'dput()' as a rather expensive operation, and there were two unrelated bad reasons for that. The first reason was reading d_lockref.count for debugging purposes, which touches the lockref cacheline (for reads) before really need to. More importantly, the debugging test in question is _wrong_, and has hidden bugs. It's true that we can only sleep when the count goes down to zero, but the test as-is hides the much more subtle bug that happens if we race with somebody else deleting the file. Anyway we _will_ touch that cacheline, but let's do it for a write and in the right routine (ie in "lockref_put_or_lock()") which annotates the costs better. So remove the misleading debug code. The other was an unnecessary access to the cacheline that contains the d_lru list, just to check whether we already were on the LRU list or not. This is exactly what we have d_flags for, so that we can avoid touching extra cache lines for the common case. So just add another bit for "is this dentry on the LRU". Finally, mark the tests properly likely/unlikely, so that the common fast-paths are dense in the instruction stream. This makes the profiles look much saner. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* constify dcache.c inlined helpers where possibleAl Viro2013-09-051-6/+6
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* vfs: check submounts and drop atomicallyMiklos Szeredi2013-09-051-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | We check submounts before doing d_drop() on a non-empty directory dentry in NFS (have_submounts()), but we do not exclude a racing mount. Process A: have_submounts() -> returns false Process B: mount() -> success Process A: d_drop() This patch prepares the ground for the fix by doing the following operations all under the same rename lock: have_submounts() shrink_dcache_parent() d_drop() This is actually an optimization since have_submounts() and shrink_dcache_parent() both traverse the same dentry tree separately. Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> CC: David Howells <dhowells@redhat.com> CC: Steven Whitehouse <swhiteho@redhat.com> CC: Trond Myklebust <Trond.Myklebust@netapp.com> CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* vfs: reimplement d_rcu_to_refcount() using lockref_get_or_lock()Linus Torvalds2013-09-021-22/+0
| | | | | | | | | | | | | | | | | | | | | This moves __d_rcu_to_refcount() from <linux/dcache.h> into fs/namei.c and re-implements it using the lockref infrastructure instead. It also adds a lot of comments about what is actually going on, because turning a dentry that was looked up using RCU into a long-lived reference counted entry is one of the more subtle parts of the rcu walk. We also used to be _particularly_ subtle in unlazy_walk() where we re-validate both the dentry and its parent using the same sequence count. We used to do it by nesting the locks and then verifying the sequence count just once. That was silly, because nested locking is expensive, but the sequence count check is not. So this just re-validates the dentry and the parent separately, avoiding the nested locking, and making the lockref lookup possible. Acked-by: Waiman Long <waiman.long@hp.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* vfs: make the dentry cache use the lockref infrastructureWaiman Long2013-08-281-10/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | This just replaces the dentry count/lock combination with the lockref structure that contains both a count and a spinlock, and does the mechanical conversion to use the lockref infrastructure. There are no semantic changes here, it's purely syntactic. The reference lockref implementation uses the spinlock exactly the same way that the old dcache code did, and the bulk of this patch is just expanding the internal "d_count" use in the dcache code to use "d_lockref.count" instead. This is purely preparation for the real change to make the reference count updates be lockless during the 3.12 merge window. [ As with the previous commit, this is a rewritten version of a concept originally from Waiman, so credit goes to him, blame for any errors goes to me. Waiman's patch had some semantic differences for taking advantage of the lockless update in dget_parent(), while this patch is intentionally a pure search-and-replace change with no semantic changes. - Linus ] Signed-off-by: Waiman Long <Waiman.Long@hp.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* cope with potentially long ->d_dname() output for shmem/hugetlbAl Viro2013-08-241-0/+1
| | | | | | | | | | dynamic_dname() is both too much and too little for those - the output may be well in excess of 64 bytes dynamic_dname() assumes to be enough (thanks to ashmem feeding really long names to shmem_file_setup()) and vsnprintf() is an overkill for those guys. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* vfs: constify dentry parameter in d_count()Peng Tao2013-07-201-1/+1
| | | | | | | | so that it can be used in places like d_compare/d_hash without causing a compiler warning. Signed-off-by: Peng Tao <tao.peng@emc.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* helper for reading ->d_countAl Viro2013-07-051-0/+5
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* Don't pass inode to ->d_hash() and ->d_compare()Linus Torvalds2013-06-291-6/+3
| | | | | | | | | | | | Instances either don't look at it at all (the majority of cases) or only want it to find the superblock (which can be had as dentry->d_sb). A few cases that want more are actually safe with dentry->d_inode - the only precaution needed is the check that it hadn't been replaced with NULL by rmdir() or by overwriting rename(), which case should be simply treated as cache miss. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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