kernel/linux.git/fs/debugfs, branch v3.18.100

dentry name snapshots

2017-08-11T16:30:11+00:00

commit 49d31c2f389acfe83417083e1208422b4091cd9e upstream. take_dentry_name_snapshot() takes a safe snapshot of dentry name; if the name is a short one, it gets copied into caller-supplied structure, otherwise an extra reference to external name is grabbed (those are never modified). In either case the pointer to stable string is stored into the same structure. dentry must be held by the caller of take_dentry_name_snapshot(), but may be freely dropped afterwards - the snapshot will stay until destroyed by release_dentry_name_snapshot(). Intended use: struct name_snapshot s; take_dentry_name_snapshot(&s, dentry); ... access s.name ... release_dentry_name_snapshot(&s); Replaces fsnotify_oldname_...(), gets used in fsnotify to obtain the name to pass down with event. Signed-off-by: Al Viro Signed-off-by: Greg Kroah-Hartman

debugfs: leave freeing a symlink body until inode eviction

2015-03-14T19:37:27+00:00

commit 0db59e59299f0b67450c5db21f7f316c8fb04e84 upstream. As it is, we have debugfs_remove() racing with symlink traversals. Supply ->evict_inode() and do freeing there - inode will remain pinned until we are done with the symlink body. And rip the idiocy with checking if dentry is positive right after we'd verified debugfs_positive(), which is a stronger check... Signed-off-by: Al Viro Signed-off-by: Sasha Levin

move d_rcu from overlapping d_child to overlapping d_alias

2014-12-16T17:39:06+00:00

commit 946e51f2bf37f1656916eb75bd0742ba33983c28 upstream. Signed-off-by: Al Viro Signed-off-by: Greg Kroah-Hartman

fs: debugfs: remove trailing whitespace

2014-07-09T23:58:21+00:00

fixes checkpatch.pl trailing whitespace errors Signed-off-by: Rahul Bedarkar Signed-off-by: Greg Kroah-Hartman

debugfs: Fix corrupted loop in debugfs_remove_recursive

2014-07-09T23:37:29+00:00

[ I'm currently running my tests on it now, and so far, after a few hours it has yet to blow up. I'll run it for 24 hours which it never succeeded in the past. ] The tracing code has a way to make directories within the debugfs file system as well as deleting them using mkdir/rmdir in the instance directory. This is very limited in functionality, such as there is no renames, and the parent directory "instance" can not be modified. The tracing code creates the instance directory from the debugfs code and then replaces the dentry->d_inode->i_op with its own to allow for mkdir/rmdir to work. When these are called, the d_entry and inode locks need to be released to call the instance creation and deletion code. That code has its own accounting and locking to serialize everything to prevent multiple users from causing harm. As the parent "instance" directory can not be modified this simplifies things. I created a stress test that creates several threads that randomly creates and deletes directories thousands of times a second. The code stood up to this test and I submitted it a while ago. Recently I added a new test that adds readers to the mix. While the instance directories were being added and deleted, readers would read from these directories and even enable tracing within them. This test was able to trigger a bug: general protection fault: 0000 [#1] PREEMPT SMP Modules linked in: ... CPU: 3 PID: 17789 Comm: rmdir Tainted: G W 3.15.0-rc2-test+ #41 Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./To be filled by O.E.M., BIOS SDBLI944.86P 05/08/2007 task: ffff88003786ca60 ti: ffff880077018000 task.ti: ffff880077018000 RIP: 0010:[] [] debugfs_remove_recursive+0x1bd/0x367 RSP: 0018:ffff880077019df8 EFLAGS: 00010246 RAX: 0000000000000002 RBX: ffff88006f0fe490 RCX: 0000000000000000 RDX: dead000000100058 RSI: 0000000000000246 RDI: ffff88003786d454 RBP: ffff88006f0fe640 R08: 0000000000000628 R09: 0000000000000000 R10: 0000000000000628 R11: ffff8800795110a0 R12: ffff88006f0fe640 R13: ffff88006f0fe640 R14: ffffffff81817d0b R15: ffffffff818188b7 FS: 00007ff13ae24700(0000) GS:ffff88007d580000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 0000003054ec7be0 CR3: 0000000076d51000 CR4: 00000000000007e0 Stack: ffff88007a41ebe0 dead000000100058 00000000fffffffe ffff88006f0fe640 0000000000000000 ffff88006f0fe678 ffff88007a41ebe0 ffff88003793a000 00000000fffffffe ffffffff810bde82 ffff88006f0fe640 ffff88007a41eb28 Call Trace: [] ? instance_rmdir+0x15b/0x1de [] ? vfs_rmdir+0x80/0xd3 [] ? do_rmdir+0xd1/0x139 [] ? trace_hardirqs_on_thunk+0x3a/0x3c [] ? system_call_fastpath+0x16/0x1b Code: fe ff ff 48 8d 75 30 48 89 df e8 c9 fd ff ff 85 c0 75 13 48 c7 c6 b8 cc d2 81 48 c7 c7 b0 cc d2 81 e8 8c 7a f5 ff 48 8b 54 24 08 <48> 8b 82 a8 00 00 00 48 89 d3 48 2d a8 00 00 00 48 89 44 24 08 RIP [] debugfs_remove_recursive+0x1bd/0x367 RSP It took a while, but every time it triggered, it was always in the same place: list_for_each_entry_safe(child, next, &parent->d_subdirs, d_u.d_child) { Where the child->d_u.d_child seemed to be corrupted. I added lots of trace_printk()s to see what was wrong, and sure enough, it was always the child's d_u.d_child field. I looked around to see what touches it and noticed that in __dentry_kill() which calls dentry_free(): static void dentry_free(struct dentry *dentry) { /* if dentry was never visible to RCU, immediate free is OK */ if (!(dentry->d_flags & DCACHE_RCUACCESS)) __d_free(&dentry->d_u.d_rcu); else call_rcu(&dentry->d_u.d_rcu, __d_free); } I also noticed that __dentry_kill() unlinks the child->d_u.child under the parent->d_lock spin_lock. Looking back at the loop in debugfs_remove_recursive() it never takes the parent->d_lock to do the list walk. Adding more tracing, I was able to prove this was the issue: ftrace-t-15385 1.... 246662024us : dentry_kill : free ffff88006d573600 rmdir-15409 2.... 246662024us : debugfs_remove_recursive : child=ffff88006d573600 next=dead000000100058 The dentry_kill freed ffff88006d573600 just as the remove recursive was walking it. In order to fix this, the list walk needs to be modified a bit to take the parent->d_lock. The safe version is no longer necessary, as every time we remove a child, the parent->d_lock must be released and the list walk must start over. Each time a child is removed, even though it may still be on the list, it should be skipped by the first check in the loop: if (!debugfs_positive(child)) continue; Cc: stable@vger.kernel.org Signed-off-by: Steven Rostedt Signed-off-by: Greg Kroah-Hartman

Merge tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

2014-04-04T22:39:39+00:00

Pull ext4 updates from Ted Ts'o: "Major changes for 3.14 include support for the newly added ZERO_RANGE and COLLAPSE_RANGE fallocate operations, and scalability improvements in the jbd2 layer and in xattr handling when the extended attributes spill over into an external block. Other than that, the usual clean ups and minor bug fixes" * tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (42 commits) ext4: fix premature freeing of partial clusters split across leaf blocks ext4: remove unneeded test of ret variable ext4: fix comment typo ext4: make ext4_block_zero_page_range static ext4: atomically set inode->i_flags in ext4_set_inode_flags() ext4: optimize Hurd tests when reading/writing inodes ext4: kill i_version support for Hurd-castrated file systems ext4: each filesystem creates and uses its own mb_cache fs/mbcache.c: doucple the locking of local from global data fs/mbcache.c: change block and index hash chain to hlist_bl_node ext4: Introduce FALLOC_FL_ZERO_RANGE flag for fallocate ext4: refactor ext4_fallocate code ext4: Update inode i_size after the preallocation ext4: fix partial cluster handling for bigalloc file systems ext4: delete path dealloc code in ext4_ext_handle_uninitialized_extents ext4: only call sync_filesystm() when remounting read-only fs: push sync_filesystem() down to the file system's remount_fs() jbd2: improve error messages for inconsistent journal heads jbd2: minimize region locked by j_list_lock in jbd2_journal_forget() jbd2: minimize region locked by j_list_lock in journal_get_create_access() ...

fs: push sync_filesystem() down to the file system's remount_fs()

2014-03-13T14:14:33+00:00

Previously, the no-op "mount -o mount /dev/xxx" operation when the file system is already mounted read-write causes an implied, unconditional syncfs(). This seems pretty stupid, and it's certainly documented or guaraunteed to do this, nor is it particularly useful, except in the case where the file system was mounted rw and is getting remounted read-only. However, it's possible that there might be some file systems that are actually depending on this behavior. In most file systems, it's probably fine to only call sync_filesystem() when transitioning from read-write to read-only, and there are some file systems where this is not needed at all (for example, for a pseudo-filesystem or something like romfs). Signed-off-by: "Theodore Ts'o" Cc: linux-fsdevel@vger.kernel.org Cc: Christoph Hellwig Cc: Artem Bityutskiy Cc: Adrian Hunter Cc: Evgeniy Dushistov Cc: Jan Kara Cc: OGAWA Hirofumi Cc: Anders Larsen Cc: Phillip Lougher Cc: Kees Cook Cc: Mikulas Patocka Cc: Petr Vandrovec Cc: xfs@oss.sgi.com Cc: linux-btrfs@vger.kernel.org Cc: linux-cifs@vger.kernel.org Cc: samba-technical@lists.samba.org Cc: codalist@coda.cs.cmu.edu Cc: linux-ext4@vger.kernel.org Cc: linux-f2fs-devel@lists.sourceforge.net Cc: fuse-devel@lists.sourceforge.net Cc: cluster-devel@redhat.com Cc: linux-mtd@lists.infradead.org Cc: jfs-discussion@lists.sourceforge.net Cc: linux-nfs@vger.kernel.org Cc: linux-nilfs@vger.kernel.org Cc: linux-ntfs-dev@lists.sourceforge.net Cc: ocfs2-devel@oss.oracle.com Cc: reiserfs-devel@vger.kernel.org

treewide: Fix typo in Documentation/DocBook

2014-02-19T13:58:17+00:00

This patch fix spelling typo in Documentation/DocBook. It is because .html and .xml files are generated by make htmldocs, I have to fix a typo within the source files. Signed-off-by: Masanari Iida Acked-by: Randy Dunlap Signed-off-by: Jiri Kosina

debugfs: use list_next_entry() in debugfs_remove_recursive()

2013-11-13T03:09:24+00:00

Change debugfs_remove_recursive() to use list_next_entry(child), no changes in generated code. Signed-off-by: Oleg Nesterov Cc: Eilon Greenstein Cc: Greg Kroah-Hartman Cc: Peter Zijlstra Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

debugfs: debugfs_remove_recursive() must not rely on list_empty(d_subdirs)

2013-07-31T16:16:31+00:00

debugfs_remove_recursive() is wrong, 1. it wrongly assumes that !list_empty(d_subdirs) means that this dir should be removed. This is not that bad by itself, but: 2. if d_subdirs does not becomes empty after __debugfs_remove() it gives up and silently fails, it doesn't even try to remove other entries. However ->d_subdirs can be non-empty because it still has the already deleted !debugfs_positive() entries. 3. simple_release_fs() is called even if __debugfs_remove() fails. Suppose we have dir1/ dir2/ file2 file1 and someone opens dir1/dir2/file2. Now, debugfs_remove_recursive(dir1/dir2) succeeds, and dir1/dir2 goes away. But debugfs_remove_recursive(dir1) silently fails and doesn't remove this directory. Because it tries to delete (the already deleted) dir1/dir2/file2 again and then fails due to "Avoid infinite loop" logic. Test-case: #!/bin/sh cd /sys/kernel/debug/tracing echo 'p:probe/sigprocmask sigprocmask' >> kprobe_events sleep 1000 < events/probe/sigprocmask/id & echo -n >| kprobe_events [ -d events/probe ] && echo "ERR!! failed to rm probe" And after that it is not possible to create another probe entry. With this patch debugfs_remove_recursive() skips !debugfs_positive() files although this is not strictly needed. The most important change is that it does not try to make ->d_subdirs empty, it simply scans the whole list(s) recursively and removes as much as possible. Link: http://lkml.kernel.org/r/20130726151256.GC19472@redhat.com Acked-by: Greg Kroah-Hartman Signed-off-by: Oleg Nesterov Signed-off-by: Steven Rostedt