4eebc40864c3b3fd71d3d1e273 parent 0143832cc96d0bf78486297aad5c8fb2c2ead02a author Steven Whitehouse 1288814467 +0000 committer Steven Whitehouse 1289825082 +0000 GFS2: Fix inode deallocation race This area of the code has always been a bit delicate due to the subtleties of lock ordering. The problem is that for "normal" alloc/dealloc, we always grab the inode locks first and the rgrp lock later. In order to ensure no races in looking up the unlinked, but still allocated inodes, we need to hold the rgrp lock when we do the lookup, which means that we can't take the inode glock. The solution is to borrow the technique already used by NFS to solve what is essentially the same problem (given an inode number, look up the inode carefully, checking that it really is in the expected state). We cannot do that directly from the allocation code (lock ordering again) so we give the job to the pre-existing delete workqueue and carry on with the allocation as normal. If we find there is no space, we do a journal flush (required anyway if space from a deallocation is to be released) which should block against the pending deallocations, so we should always get the space back. Signed-off-by: Steven Whitehouse ˆÄI’'x