The patch titled xfs: extend completions to provide XFS object flush requirements has been added to the -mm tree. Its filename is xfs-extend-completions-to-provide-xfs-object-flush-requirements.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: xfs: extend completions to provide XFS object flush requirements From: Dave Chinner <david@xxxxxxxxxxxxx> XFS object flushing doesn't quite match existing completion semantics. It mixed exclusive access with completion. That is, we need to mark an object as being flushed before flushing it to disk, and then block any other attempt to flush it until the completion occurs. We do this but adding an extra count to the completion before we start using them. However, we still need to determine if there is a completion in progress, and allow no-blocking attempts fo completions to decrement the count. To do this we introduce: int try_wait_for_completion(struct completion *x) returns a failure status if done == 0, otherwise decrements done to zero and returns a "started" status. This is provided to allow counted completions to begin safely while holding object locks in inverted order. int completion_done(struct completion *x) returns 1 if there is no waiter, 0 if there is a waiter (i.e. a completion in progress). This replaces the use of semaphores for providing this exclusion and completion mechanism. Signed-off-by: Dave Chinner <david@xxxxxxxxxxxxx> Cc: Timothy Shimmin <tes@xxxxxxx> Cc: Lachlan McIlroy <lachlan@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/completion.h | 45 +++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) diff -puN include/linux/completion.h~xfs-extend-completions-to-provide-xfs-object-flush-requirements include/linux/completion.h --- a/include/linux/completion.h~xfs-extend-completions-to-provide-xfs-object-flush-requirements +++ a/include/linux/completion.h @@ -55,4 +55,49 @@ extern void complete_all(struct completi #define INIT_COMPLETION(x) ((x).done = 0) + +/** + * try_wait_for_completion - try to decrement a completion without blocking + * @x: completion structure + * + * Returns: 0 if a decrement cannot be done without blocking + * 1 if a decrement succeeded. + * + * If a completion is being used as a counting completion, + * attempt to decrement the counter without blocking. This + * enables us to avoid waiting if the resource the completion + * is protecting is not available. + */ +static inline bool try_wait_for_completion(struct completion *x) +{ + int ret = 1; + + spin_lock_irq(&x->wait.lock); + if (!x->done) + ret = 0; + else + x->done--; + spin_unlock_irq(&x->wait.lock); + return ret; +} + +/** + * completion_done - Test to see if a completion has any waiters + * @x: completion structure + * + * Returns: 0 if there are waiters (wait_for_completion() in progress) + * 1 if there are no waiters. + * + */ +static inline bool completion_done(struct completion *x) +{ + int ret = 1; + + spin_lock_irq(&x->wait.lock); + if (!x->done) + ret = 0; + spin_unlock_irq(&x->wait.lock); + return ret; +} + #endif _ Patches currently in -mm which might be from david@xxxxxxxxxxxxx are xfs-clean-up-stale-references-to-semaphores.patch xfs-replace-the-xfs-buf-iodone-semaphore-with-a-completion.patch xfs-extend-completions-to-provide-xfs-object-flush-requirements.patch xfs-replace-inode-flush-semaphore-with-a-completion.patch xfs-replace-dquot-flush-semaphore-with-a-completion.patch xfs-remove-the-sema_t-from-xfs.patch xfs-fix-disabled-xfs-posix-acl-handling.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html