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2022-12-09ext4: fix deadlock due to mbcache entry corruptionJan Kara1-2/+7
When manipulating xattr blocks, we can deadlock infinitely looping inside ext4_xattr_block_set() where we constantly keep finding xattr block for reuse in mbcache but we are unable to reuse it because its reference count is too big. This happens because cache entry for the xattr block is marked as reusable (e_reusable set) although its reference count is too big. When this inconsistency happens, this inconsistent state is kept indefinitely and so ext4_xattr_block_set() keeps retrying indefinitely. The inconsistent state is caused by non-atomic update of e_reusable bit. e_reusable is part of a bitfield and e_reusable update can race with update of e_referenced bit in the same bitfield resulting in loss of one of the updates. Fix the problem by using atomic bitops instead. This bug has been around for many years, but it became *much* easier to hit after commit 65f8b80053a1 ("ext4: fix race when reusing xattr blocks"). Cc: stable@vger.kernel.org Fixes: 6048c64b2609 ("mbcache: add reusable flag to cache entries") Fixes: 65f8b80053a1 ("ext4: fix race when reusing xattr blocks") Reported-and-tested-by: Jeremi Piotrowski <jpiotrowski@linux.microsoft.com> Reported-by: Thilo Fromm <t-lo@linux.microsoft.com> Link: https://lore.kernel.org/r/c77bf00f-4618-7149-56f1-b8d1664b9d07@linux.microsoft.com/ Signed-off-by: Jan Kara <jack@suse.cz> Reviewed-by: Andreas Dilger <adilger@dilger.ca> Link: https://lore.kernel.org/r/20221123193950.16758-1-jack@suse.cz Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2022-08-03mbcache: automatically delete entries from cache on freeingJan Kara1-8/+16
Use the fact that entries with elevated refcount are not removed from the hash and just move removal of the entry from the hash to the entry freeing time. When doing this we also change the generic code to hold one reference to the cache entry, not two of them, which makes code somewhat more obvious. Signed-off-by: Jan Kara <jack@suse.cz> Link: https://lore.kernel.org/r/20220712105436.32204-10-jack@suse.cz Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2022-08-03mbcache: Remove mb_cache_entry_delete()Jan Kara1-1/+0
Nobody uses mb_cache_entry_delete() anymore. Remove it. Signed-off-by: Jan Kara <jack@suse.cz> Link: https://lore.kernel.org/r/20220712105436.32204-9-jack@suse.cz Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2022-08-03mbcache: add functions to delete entry if unusedJan Kara1-1/+9
Add function mb_cache_entry_delete_or_get() to delete mbcache entry if it is unused and also add a function to wait for entry to become unused - mb_cache_entry_wait_unused(). We do not share code between the two deleting function as one of them will go away soon. CC: stable@vger.kernel.org Fixes: 82939d7999df ("ext4: convert to mbcache2") Signed-off-by: Jan Kara <jack@suse.cz> Link: https://lore.kernel.org/r/20220712105436.32204-2-jack@suse.cz Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2017-11-02License cleanup: add SPDX GPL-2.0 license identifier to files with no licenseGreg Kroah-Hartman1-0/+1
Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-06-22mbcache: make mbcache naming more genericTahsin Erdogan1-6/+5
Make names more generic so that mbcache usage is not limited to block sharing. In a subsequent patch in the series ("ext4: xattr inode deduplication"), we start using the mbcache code for sharing xattr inodes. With that patch, old mb_cache_entry.e_block field could be holding either a block number or an inode number. Signed-off-by: Tahsin Erdogan <tahsin@google.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-02-23mbcache: add reusable flag to cache entriesAndreas Gruenbacher1-1/+4
To reduce amount of damage caused by single bad block, we limit number of inodes sharing an xattr block to 1024. Thus there can be more xattr blocks with the same contents when there are lots of files with the same extended attributes. These xattr blocks naturally result in hash collisions and can form long hash chains and we unnecessarily check each such block only to find out we cannot use it because it is already shared by too many inodes. Add a reusable flag to cache entries which is cleared when a cache entry has reached its maximum refcount. Cache entries which are not marked reusable are skipped by mb_cache_entry_find_{first,next}. This significantly speeds up mbcache when there are many same xattr blocks. For example for xattr-bench with 5 values and each process handling 20000 files, the run for 64 processes is 25x faster with this patch. Even for 8 processes the speedup is almost 3x. We have also verified that for situations where there is only one xattr block of each kind, the patch doesn't have a measurable cost. [JK: Remove handling of setting the same value since it is not needed anymore, check for races in e_reusable setting, improve changelog, add measurements] Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-02-23mbcache: get rid of _e_hash_list_headAndreas Gruenbacher1-6/+2
Get rid of field _e_hash_list_head in cache entries and add bit field e_referenced instead. Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-02-23mbcache2: rename to mbcacheJan Kara1-0/+53
Since old mbcache code is gone, let's rename new code to mbcache since number 2 is now meaningless. This is just a mechanical replacement. Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2016-02-22mbcache: remove mbcacheJan Kara1-55/+0
Both ext2 and ext4 are now converted to mbcache2. Remove the old mbcache code. Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2014-03-19fs/mbcache.c: change block and index hash chain to hlist_bl_nodeT Makphaibulchoke1-5/+7
This patch changes each mb_cache's both block and index hash chains to use a hlist_bl_node, which contains a built-in lock. This is the first step in decoupling of locks serializing accesses to mb_cache global data and each mb_cache_entry local data. Signed-off-by: T. Makphaibulchoke <tmac@hp.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-01-10ext2: Resolve 'dereferencing pointer to incomplete type' when enabling ↵Josh Hunt1-0/+11
EXT2_XATTR_DEBUG When I enable EXT2_XATTR_DEBUG in fs/ext2/xattr.c I get a build error stating the following: CC fs/ext2/xattr.o fs/ext2/xattr.c: In function 'ext2_xattr_cache_insert': fs/ext2/xattr.c:841: error: dereferencing pointer to incomplete type fs/ext2/xattr.c:846: error: dereferencing pointer to incomplete type make[2]: *** [fs/ext2/xattr.o] Error 1 make[1]: *** [fs/ext2] Error 2 make: *** [fs] Error 2 These lines reference ext2_xattr_cache->c_entry_count which is defined in struct mb_cache. struct mb_cache is currently only defined in fs/mbcache.c. Moving struct mb_cache definition to include/linux/mbcache.h to resolve the issue. Signed-off-by: Josh Hunt <johunt@akamai.com> Signed-off-by: Jan Kara <jack@suse.cz>
2010-08-10mbcache: Remove unused featuresAndreas Gruenbacher1-15/+5
The mbcache code was written to support a variable number of indexes, but all the existing users use exactly one index. Simplify to code to support only that case. There are also no users of the cache entry free operation, and none of the users keep extra data in cache entries. Remove those features as well. Signed-off-by: Andreas Gruenbacher <agruen@suse.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2008-04-16vfs: fix possible deadlock in ext2, ext3, ext4 when using xattrsJan Kara1-1/+1
mb_cache_entry_alloc() was allocating cache entries with GFP_KERNEL. But filesystems are calling this function while holding xattr_sem so possible recursion into the fs violates locking ordering of xattr_sem and transaction start / i_mutex for ext2-4. Change mb_cache_entry_alloc() so that filesystems can specify desired gfp mask and use GFP_NOFS from all of them. Signed-off-by: Jan Kara <jack@suse.cz> Reported-by: Dave Jones <davej@redhat.com> Cc: <linux-ext4@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2005-10-28[PATCH] gfp_t: fs/*Al Viro1-1/+1
- ->releasepage() annotated (s/int/gfp_t), instances updated - missing gfp_t in fs/* added - fixed misannotation from the original sweep caught by bitwise checks: XFS used __nocast both for gfp_t and for flags used by XFS allocator. The latter left with unsigned int __nocast; we might want to add a different type for those but for now let's leave them alone. That, BTW, is a case when __nocast use had been actively confusing - it had been used in the same code for two different and similar types, with no way to catch misuses. Switch of gfp_t to bitwise had caught that immediately... One tricky bit is left alone to be dealt with later - mapping->flags is a mix of gfp_t and error indications. Left alone for now. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-07-28[PATCH] mbcache: Remove unused mb_cache_shrink parameterAndreas Gruenbacher1-1/+1
The cache parameter to mb_cache_shrink isn't used. We may as well remove it. Signed-off-by: Andreas Gruenbacher <agruen@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-17Linux-2.6.12-rc2v2.6.12-rc2Linus Torvalds1-0/+52
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!