Messages in this thread |  | | Date | Thu, 26 Apr 2001 20:12:36 +0200 | From | Andrea Arcangeli <> | Subject | Re: [PATCH] SMP race in ext2 - metadata corruption. |
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On Thu, Apr 26, 2001 at 11:45:47AM -0400, Alexander Viro wrote: > Ext2 does getblk+wait_on_buffer for new metadata blocks before > filling them with zeroes. While that is enough for single-processor, > on SMP we have the following race: > > getblk gives us unlocked, non-uptodate bh > wait_on_buffer() does nothing > read from device locks it and starts IO > we zero it out. > on-disk data overwrites our zeroes. > we mark it dirty > bdflush writes the old data (_not_ zeroes) back to disk. > > Result: crap in metadata block. Proposed fix: lock_buffer()/unlock_buffer() > around memset()/mark_buffer_uptodate() instead of wait_on_buffer() before > them. > > Patch against 2.4.4-pre7 follows. Please, apply.
correct. I bet other fs are affected as well btw.
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