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path: root/fs/reiserfs/resize.c
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2009-09-14reiserfs: kill-the-BKLFrederic Weisbecker
This patch is an attempt to remove the Bkl based locking scheme from reiserfs and is intended. It is a bit inspired from an old attempt by Peter Zijlstra: http://lkml.indiana.edu/hypermail/linux/kernel/0704.2/2174.html The bkl is heavily used in this filesystem to prevent from concurrent write accesses on the filesystem. Reiserfs makes a deep use of the specific properties of the Bkl: - It can be acqquired recursively by a same task - It is released on the schedule() calls and reacquired when schedule() returns The two properties above are a roadmap for the reiserfs write locking so it's very hard to simply replace it with a common mutex. - We need a recursive-able locking unless we want to restructure several blocks of the code. - We need to identify the sites where the bkl was implictly relaxed (schedule, wait, sync, etc...) so that we can in turn release and reacquire our new lock explicitly. Such implicit releases of the lock are often required to let other resources producer/consumer do their job or we can suffer unexpected starvations or deadlocks. So the new lock that replaces the bkl here is a per superblock mutex with a specific property: it can be acquired recursively by a same task, like the bkl. For such purpose, we integrate a lock owner and a lock depth field on the superblock information structure. The first axis on this patch is to turn reiserfs_write_(un)lock() function into a wrapper to manage this mutex. Also some explicit calls to lock_kernel() have been converted to reiserfs_write_lock() helpers. The second axis is to find the important blocking sites (schedule...(), wait_on_buffer(), sync_dirty_buffer(), etc...) and then apply an explicit release of the write lock on these locations before blocking. Then we can safely wait for those who can give us resources or those who need some. Typically this is a fight between the current writer, the reiserfs workqueue (aka the async commiter) and the pdflush threads. The third axis is a consequence of the second. The write lock is usually on top of a lock dependency chain which can include the journal lock, the flush lock or the commit lock. So it's dangerous to release and trying to reacquire the write lock while we still hold other locks. This is fine with the bkl: T1 T2 lock_kernel() mutex_lock(A) unlock_kernel() // do something lock_kernel() mutex_lock(A) -> already locked by T1 schedule() (and then unlock_kernel()) lock_kernel() mutex_unlock(A) .... This is not fine with a mutex: T1 T2 mutex_lock(write) mutex_lock(A) mutex_unlock(write) // do something mutex_lock(write) mutex_lock(A) -> already locked by T1 schedule() mutex_lock(write) -> already locked by T2 deadlock The solution in this patch is to provide a helper which releases the write lock and sleep a bit if we can't lock a mutex that depend on it. It's another simulation of the bkl behaviour. The last axis is to locate the fs callbacks that are called with the bkl held, according to Documentation/filesystem/Locking. Those are: - reiserfs_remount - reiserfs_fill_super - reiserfs_put_super Reiserfs didn't need to explicitly lock because of the context of these callbacks. But now we must take care of that with the new locking. After this patch, reiserfs suffers from a slight performance regression (for now). On UP, a high volume write with dd reports an average of 27 MB/s instead of 30 MB/s without the patch applied. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Reviewed-by: Ingo Molnar <mingo@elte.hu> Cc: Jeff Mahoney <jeffm@suse.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Bron Gondwana <brong@fastmail.fm> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> LKML-Reference: <1239070789-13354-1-git-send-email-fweisbec@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-06-24reiserfs: remove stray unlock_super in reiserfs_resizeChristoph Hellwig
Reiserfs doesn't use lock_super anywhere internally, and ->remount_fs which calls reiserfs_resize does have it currently but also expects it to be held on return, so there's no business for the unlock_super here. Signed-off-by: Christoph Hellwig <hch@lst.de> Acked by Edward Shishkin <edward.shishkin@gmail.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-03-30reiserfs: strip trailing whitespaceJeff Mahoney
This patch strips trailing whitespace from the reiserfs code. Signed-off-by: Jeff Mahoney <jeffm@suse.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19reiserfs: ignore on disk s_bmap_nr valueJeff Mahoney
Implement support for file systems larger than 8 TiB. The reiserfs superblock contains a 16 bit value for counting the number of bitmap blocks. The rest of the disk format supports file systems up to 2^32 blocks, but the bitmap block limitation artificially limits this to 8 TiB with a 4KiB block size. Rather than trust the superblock's 16-bit bitmap block count, we calculate it dynamically based on the number of blocks in the file system. When an incorrect value is observed in the superblock, it is zeroed out, ensuring that older kernels will not be able to mount the file system. Userspace support has already been implemented and shipped in reiserfsprogs 3.6.20. Signed-off-by: Jeff Mahoney <jeffm@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19reiserfs: remove first_zero_hintJeff Mahoney
The first_zero_hint metadata caching was never actually used, and it's of dubious optimization quality. This patch removes it. It doesn't actually shrink the size of the reiserfs_bitmap_info struct, since that doesn't work with block sizes larger than 8K. There was a big fixme in there, and with all the work lately in allowing block size > page size, I might as well kill the fixme as well. Signed-off-by: Jeff Mahoney <jeffm@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19reiserfs: fix memset byte count during resizeJeff Mahoney
Correct the memset in reiserfs_resize to clear the memory allocated for the new bitmap info structs. Previously, it would clear the memory used by the old size. Depending on the contents of memory, this could cause incorrect caching behavior for bitmap blocks in the newly allocated area. Signed-off-by: Jeff Mahoney <jeffm@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08reiserfs: possible null pointer dereference during resizeDmitriy Monakhov
sb_read may return NULL, let's explicitly check it. If so free new bitmap blocks array, after this we may safely exit as it done above during bitmap allocation. Signed-off-by: Dmitriy Monakhov <dmonakhov@openvz.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2006-10-01[PATCH] reiserfs: on-demand bitmap loadingJeff Mahoney
This is the patch the three previous ones have been leading up to. It changes the behavior of ReiserFS from loading and caching all the bitmaps as special, to treating the bitmaps like any other bit of metadata and just letting the system-wide caches figure out what to hang on to. Buffer heads are allocated on the fly, so there is no need to retain pointers to all of them. The caching of the metadata occurs when the data is read and updated, and is considered invalid and uncached until then. I needed to remove the vs-4040 check for performing a duplicate operation on a particular bit. The reason is that while the other sites for working with bitmaps are allowed to schedule, is_reusable() is called from do_balance(), which will panic if a schedule occurs in certain places. The benefit of on-demand bitmaps clearly outweighs a sanity check that depends on a compile-time option that is discouraged. [akpm@osdl.org: warning fix] Signed-off-by: Jeff Mahoney <jeffm@suse.com> Cc: <reiserfs-dev@namesys.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-01[PATCH] reiserfs: reorganize bitmap loading functionsJeff Mahoney
This patch moves the bitmap loading code from super.c to bitmap.c The code is also restructured somewhat. The only difference between new format bitmaps and old format bitmaps is where they are. That's a two liner before loading the block to use the correct one. There's no need for an entirely separate code path. The load path is generally the same, with the pattern being to throw out a bunch of requests and then wait for them, then cache the metadata from the contents. Again, like the previous patches, the purpose is to set up for later ones. Update: There was a bug in the previously posted version of this that resulted in corruption. The problem was that bitmap 0 on new format file systems must be treated specially, and wasn't. A stupid bug with an easy fix. This is hopefully the last fix for the disaster that is the reiserfs bitmap patch set. If a bitmap block was full, first_zero_hint would end up at zero since it would never be changed from it's zeroed out value. This just sets it beyond the end of the bitmap block. If any bits are freed, it will be reset to a valid bit. When info->free_count = 0, then we already know it's full. Signed-off-by: Jeff Mahoney <jeffm@suse.com> Cc: <reiserfs-dev@namesys.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-01[PATCH] reiserfs: clean up bitmap block buffer head referencesJeff Mahoney
Similar to the SB_JOURNAL cleanup that was accepted a while ago, this patch uses a temporary variable for buffer head references from the bitmap info array. This makes the code much more readable in some areas. It also uses proper reference counting, doing a get_bh() after using the pointer from the array and brelse()'ing it later. This may seem silly, but a later patch will replace the simple temporary variables with an actual read, so the reference freeing will be used then. Signed-off-by: Jeff Mahoney <jeffm@suse.com> Cc: <reiserfs-dev@namesys.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-07-13reiserfs: run scripts/Lindent on reiserfs codeLinus Torvalds
This was a pure indentation change, using: scripts/Lindent fs/reiserfs/*.c include/linux/reiserfs_*.h to make reiserfs match the regular Linux indentation style. As Jeff Mahoney <jeffm@suse.com> writes: The ReiserFS code is a mix of a number of different coding styles, sometimes different even from line-to-line. Since the code has been relatively stable for quite some time and there are few outstanding patches to be applied, it is time to reformat the code to conform to the Linux style standard outlined in Documentation/CodingStyle. This patch contains the result of running scripts/Lindent against fs/reiserfs/*.c and include/linux/reiserfs_*.h. There are places where the code can be made to look better, but I'd rather keep those patches separate so that there isn't a subtle by-hand hand accident in the middle of a huge patch. To be clear: This patch is reformatting *only*. A number of patches may follow that continue to make the code more consistent with the Linux coding style. Hans wasn't particularly enthusiastic about these patches, but said he wouldn't really oppose them either. Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-16Linux-2.6.12-rc2Linus Torvalds
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!