Andrew Morton wrote:

On Fri, 04 May 2007 10:18:12 +0400 Alex Tomas [off-list ref] wrote:

quoted

Andrew Morton wrote:

quoted

Yes, there can be issues with needing to allocate journal space within the
context of a commit.  But

no-no, this isn't required. we only need to mark pages/blocks within
transaction, otherwise race is possible when we allocate blocks in transaction,
then transacton starts to commit, then we mark pages/blocks to be flushed
before commit.

I don't understand.  Can you please describe the race in more detail?

if I understood your idea right, then in data=ordered mode, commit thread writes
all dirty mapped blocks before real commit.

say, we have two threads: t1 is a thread doing flushing and t2 is a commit thread

t1					t2
find dirty inode I
find some dirty unallocated blocks
journal_start()
allocate blocks
attach them to I
journal_stop()

					going to commit
					find inode I dirty
					do NOT find these blocks because they're
					  allocated only, but pages/bhs aren't mapped
					  to them
					start commit


map pages/bhs to just allocate blocks


so, either we mark pages/bhs someway within journal_start()--journal_stop() or
commit thread should do lookup for all dirty pages. the latter doesn't sound nice, IMHO.

thanks, Alex