diff options
| -rw-r--r-- | Documentation/filesystems/iomap/operations.rst | 4 | ||||
| -rw-r--r-- | fs/backing-file.c | 6 | ||||
| -rw-r--r-- | fs/iomap/direct-io.c | 197 | ||||
| -rw-r--r-- | include/linux/fs.h | 43 | ||||
| -rw-r--r-- | io_uring/rw.c | 16 |
5 files changed, 114 insertions, 152 deletions
diff --git a/Documentation/filesystems/iomap/operations.rst b/Documentation/filesystems/iomap/operations.rst index 64f4baf5750e..da982ca7e413 100644 --- a/Documentation/filesystems/iomap/operations.rst +++ b/Documentation/filesystems/iomap/operations.rst @@ -490,10 +490,6 @@ These ``struct kiocb`` flags are significant for direct I/O with iomap: Only meaningful for asynchronous I/O, and only if the entire I/O can be issued as a single ``struct bio``. - * ``IOCB_DIO_CALLER_COMP``: Try to run I/O completion from the caller's - process context. - See ``linux/fs.h`` for more details. - Filesystems should call ``iomap_dio_rw`` from ``->read_iter`` and ``->write_iter``, and set ``FMODE_CAN_ODIRECT`` in the ``->open`` function for the file. diff --git a/fs/backing-file.c b/fs/backing-file.c index 15a7f8031084..2a86bb6fcd13 100644 --- a/fs/backing-file.c +++ b/fs/backing-file.c @@ -227,12 +227,6 @@ ssize_t backing_file_write_iter(struct file *file, struct iov_iter *iter, !(file->f_mode & FMODE_CAN_ODIRECT)) return -EINVAL; - /* - * Stacked filesystems don't support deferred completions, don't copy - * this property in case it is set by the issuer. - */ - flags &= ~IOCB_DIO_CALLER_COMP; - old_cred = override_creds(ctx->cred); if (is_sync_kiocb(iocb)) { rwf_t rwf = iocb_to_rw_flags(flags); diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c index 8b2f9fb89eb3..00ab58d55c54 100644 --- a/fs/iomap/direct-io.c +++ b/fs/iomap/direct-io.c @@ -16,9 +16,8 @@ * Private flags for iomap_dio, must not overlap with the public ones in * iomap.h: */ -#define IOMAP_DIO_NO_INVALIDATE (1U << 25) -#define IOMAP_DIO_CALLER_COMP (1U << 26) -#define IOMAP_DIO_INLINE_COMP (1U << 27) +#define IOMAP_DIO_NO_INVALIDATE (1U << 26) +#define IOMAP_DIO_COMP_WORK (1U << 27) #define IOMAP_DIO_WRITE_THROUGH (1U << 28) #define IOMAP_DIO_NEED_SYNC (1U << 29) #define IOMAP_DIO_WRITE (1U << 30) @@ -140,11 +139,6 @@ ssize_t iomap_dio_complete(struct iomap_dio *dio) } EXPORT_SYMBOL_GPL(iomap_dio_complete); -static ssize_t iomap_dio_deferred_complete(void *data) -{ - return iomap_dio_complete(data); -} - static void iomap_dio_complete_work(struct work_struct *work) { struct iomap_dio *dio = container_of(work, struct iomap_dio, aio.work); @@ -179,33 +173,33 @@ static void iomap_dio_done(struct iomap_dio *dio) WRITE_ONCE(dio->submit.waiter, NULL); blk_wake_io_task(waiter); - } else if (dio->flags & IOMAP_DIO_INLINE_COMP) { - WRITE_ONCE(iocb->private, NULL); - iomap_dio_complete_work(&dio->aio.work); - } else if (dio->flags & IOMAP_DIO_CALLER_COMP) { - /* - * If this dio is flagged with IOMAP_DIO_CALLER_COMP, then - * schedule our completion that way to avoid an async punt to a - * workqueue. - */ - /* only polled IO cares about private cleared */ - iocb->private = dio; - iocb->dio_complete = iomap_dio_deferred_complete; + return; + } - /* - * Invoke ->ki_complete() directly. We've assigned our - * dio_complete callback handler, and since the issuer set - * IOCB_DIO_CALLER_COMP, we know their ki_complete handler will - * notice ->dio_complete being set and will defer calling that - * handler until it can be done from a safe task context. - * - * Note that the 'res' being passed in here is not important - * for this case. The actual completion value of the request - * will be gotten from dio_complete when that is run by the - * issuer. - */ - iocb->ki_complete(iocb, 0); - } else { + /* + * Always run error completions in user context. These are not + * performance critical and some code relies on taking sleeping locks + * for error handling. + */ + if (dio->error) + dio->flags |= IOMAP_DIO_COMP_WORK; + + /* + * Never invalidate pages from this context to avoid deadlocks with + * buffered I/O completions when called from the ioend workqueue, + * or avoid sleeping when called directly from ->bi_end_io. + * Tough luck if you hit the tiny race with someone dirtying the range + * right between this check and the actual completion. + */ + if ((dio->flags & IOMAP_DIO_WRITE) && + !(dio->flags & IOMAP_DIO_COMP_WORK)) { + if (dio->iocb->ki_filp->f_mapping->nrpages) + dio->flags |= IOMAP_DIO_COMP_WORK; + else + dio->flags |= IOMAP_DIO_NO_INVALIDATE; + } + + if (dio->flags & IOMAP_DIO_COMP_WORK) { struct inode *inode = file_inode(iocb->ki_filp); /* @@ -216,7 +210,11 @@ static void iomap_dio_done(struct iomap_dio *dio) */ INIT_WORK(&dio->aio.work, iomap_dio_complete_work); queue_work(inode->i_sb->s_dio_done_wq, &dio->aio.work); + return; } + + WRITE_ONCE(iocb->private, NULL); + iomap_dio_complete_work(&dio->aio.work); } void iomap_dio_bio_end_io(struct bio *bio) @@ -252,16 +250,9 @@ u32 iomap_finish_ioend_direct(struct iomap_ioend *ioend) /* * Try to avoid another context switch for the completion given * that we are already called from the ioend completion - * workqueue, but never invalidate pages from this thread to - * avoid deadlocks with buffered I/O completions. Tough luck if - * you hit the tiny race with someone dirtying the range now - * between this check and the actual completion. + * workqueue. */ - if (!dio->iocb->ki_filp->f_mapping->nrpages) { - dio->flags |= IOMAP_DIO_INLINE_COMP; - dio->flags |= IOMAP_DIO_NO_INVALIDATE; - } - dio->flags &= ~IOMAP_DIO_CALLER_COMP; + dio->flags &= ~IOMAP_DIO_COMP_WORK; iomap_dio_done(dio); } @@ -306,23 +297,6 @@ static int iomap_dio_zero(const struct iomap_iter *iter, struct iomap_dio *dio, return 0; } -/* - * Use a FUA write if we need datasync semantics and this is a pure data I/O - * that doesn't require any metadata updates (including after I/O completion - * such as unwritten extent conversion) and the underlying device either - * doesn't have a volatile write cache or supports FUA. - * This allows us to avoid cache flushes on I/O completion. - */ -static inline bool iomap_dio_can_use_fua(const struct iomap *iomap, - struct iomap_dio *dio) -{ - if (iomap->flags & (IOMAP_F_SHARED | IOMAP_F_DIRTY)) - return false; - if (!(dio->flags & IOMAP_DIO_WRITE_THROUGH)) - return false; - return !bdev_write_cache(iomap->bdev) || bdev_fua(iomap->bdev); -} - static int iomap_dio_bio_iter(struct iomap_iter *iter, struct iomap_dio *dio) { const struct iomap *iomap = &iter->iomap; @@ -351,7 +325,24 @@ static int iomap_dio_bio_iter(struct iomap_iter *iter, struct iomap_dio *dio) return -EINVAL; if (dio->flags & IOMAP_DIO_WRITE) { - bio_opf |= REQ_OP_WRITE; + bool need_completion_work = true; + + switch (iomap->type) { + case IOMAP_MAPPED: + /* + * Directly mapped I/O does not inherently need to do + * work at I/O completion time. But there are various + * cases below where this will get set again. + */ + need_completion_work = false; + break; + case IOMAP_UNWRITTEN: + dio->flags |= IOMAP_DIO_UNWRITTEN; + need_zeroout = true; + break; + default: + break; + } if (iomap->flags & IOMAP_F_ATOMIC_BIO) { /* @@ -364,35 +355,54 @@ static int iomap_dio_bio_iter(struct iomap_iter *iter, struct iomap_dio *dio) bio_opf |= REQ_ATOMIC; } - if (iomap->type == IOMAP_UNWRITTEN) { - dio->flags |= IOMAP_DIO_UNWRITTEN; - need_zeroout = true; - } - - if (iomap->flags & IOMAP_F_SHARED) + if (iomap->flags & IOMAP_F_SHARED) { + /* + * Unsharing of needs to update metadata at I/O + * completion time. + */ + need_completion_work = true; dio->flags |= IOMAP_DIO_COW; + } - if (iomap->flags & IOMAP_F_NEW) + if (iomap->flags & IOMAP_F_NEW) { + /* + * Newly allocated blocks might need recording in + * metadata at I/O completion time. + */ + need_completion_work = true; need_zeroout = true; - else if (iomap->type == IOMAP_MAPPED && - iomap_dio_can_use_fua(iomap, dio)) - bio_opf |= REQ_FUA; + } - if (!(bio_opf & REQ_FUA)) - dio->flags &= ~IOMAP_DIO_WRITE_THROUGH; + /* + * Use a FUA write if we need datasync semantics and this is a + * pure overwrite that doesn't require any metadata updates. + * + * This allows us to avoid cache flushes on I/O completion. + */ + if (dio->flags & IOMAP_DIO_WRITE_THROUGH) { + if (!need_completion_work && + !(iomap->flags & IOMAP_F_DIRTY) && + (!bdev_write_cache(iomap->bdev) || + bdev_fua(iomap->bdev))) + bio_opf |= REQ_FUA; + else + dio->flags &= ~IOMAP_DIO_WRITE_THROUGH; + } /* - * We can only do deferred completion for pure overwrites that + * We can only do inline completion for pure overwrites that * don't require additional I/O at completion time. * - * This rules out writes that need zeroing or extent conversion, - * extend the file size, or issue metadata I/O or cache flushes - * during completion processing. + * This rules out writes that need zeroing or metdata updates to + * convert unwritten or shared extents. + * + * Writes that extend i_size are also not supported, but this is + * handled in __iomap_dio_rw(). */ - if (need_zeroout || (pos >= i_size_read(inode)) || - ((dio->flags & IOMAP_DIO_NEED_SYNC) && - !(bio_opf & REQ_FUA))) - dio->flags &= ~IOMAP_DIO_CALLER_COMP; + if (need_completion_work) + dio->flags |= IOMAP_DIO_COMP_WORK; + + bio_opf |= REQ_OP_WRITE; } else { bio_opf |= REQ_OP_READ; } @@ -413,7 +423,7 @@ static int iomap_dio_bio_iter(struct iomap_iter *iter, struct iomap_dio *dio) * ones we set for inline and deferred completions. If none of those * are available for this IO, clear the polled flag. */ - if (!(dio->flags & (IOMAP_DIO_INLINE_COMP|IOMAP_DIO_CALLER_COMP))) + if (dio->flags & IOMAP_DIO_COMP_WORK) dio->iocb->ki_flags &= ~IOCB_HIPRI; if (need_zeroout) { @@ -653,9 +663,6 @@ __iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, dio->flags |= IOMAP_DIO_FSBLOCK_ALIGNED; if (iov_iter_rw(iter) == READ) { - /* reads can always complete inline */ - dio->flags |= IOMAP_DIO_INLINE_COMP; - if (iomi.pos >= dio->i_size) goto out_free_dio; @@ -669,15 +676,6 @@ __iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, iomi.flags |= IOMAP_WRITE; dio->flags |= IOMAP_DIO_WRITE; - /* - * Flag as supporting deferred completions, if the issuer - * groks it. This can avoid a workqueue punt for writes. - * We may later clear this flag if we need to do other IO - * as part of this IO completion. - */ - if (iocb->ki_flags & IOCB_DIO_CALLER_COMP) - dio->flags |= IOMAP_DIO_CALLER_COMP; - if (dio_flags & IOMAP_DIO_OVERWRITE_ONLY) { ret = -EAGAIN; if (iomi.pos >= dio->i_size || @@ -707,6 +705,12 @@ __iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, } /* + * i_size updates must to happen from process context. + */ + if (iomi.pos + iomi.len > dio->i_size) + dio->flags |= IOMAP_DIO_COMP_WORK; + + /* * Try to invalidate cache pages for the range we are writing. * If this invalidation fails, let the caller fall back to * buffered I/O. @@ -778,9 +782,14 @@ __iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, * If all the writes we issued were already written through to the * media, we don't need to flush the cache on IO completion. Clear the * sync flag for this case. + * + * Otherwise clear the inline completion flag if any sync work is + * needed, as that needs to be performed from process context. */ if (dio->flags & IOMAP_DIO_WRITE_THROUGH) dio->flags &= ~IOMAP_DIO_NEED_SYNC; + else if (dio->flags & IOMAP_DIO_NEED_SYNC) + dio->flags |= IOMAP_DIO_COMP_WORK; /* * We are about to drop our additional submission reference, which diff --git a/include/linux/fs.h b/include/linux/fs.h index c895146c1444..e210d2d8af53 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -367,23 +367,9 @@ struct readahead_control; #define IOCB_NOIO (1 << 20) /* can use bio alloc cache */ #define IOCB_ALLOC_CACHE (1 << 21) -/* - * IOCB_DIO_CALLER_COMP can be set by the iocb owner, to indicate that the - * iocb completion can be passed back to the owner for execution from a safe - * context rather than needing to be punted through a workqueue. If this - * flag is set, the bio completion handling may set iocb->dio_complete to a - * handler function and iocb->private to context information for that handler. - * The issuer should call the handler with that context information from task - * context to complete the processing of the iocb. Note that while this - * provides a task context for the dio_complete() callback, it should only be - * used on the completion side for non-IO generating completions. It's fine to - * call blocking functions from this callback, but they should not wait for - * unrelated IO (like cache flushing, new IO generation, etc). - */ -#define IOCB_DIO_CALLER_COMP (1 << 22) /* kiocb is a read or write operation submitted by fs/aio.c. */ -#define IOCB_AIO_RW (1 << 23) -#define IOCB_HAS_METADATA (1 << 24) +#define IOCB_AIO_RW (1 << 22) +#define IOCB_HAS_METADATA (1 << 23) /* for use in trace events */ #define TRACE_IOCB_STRINGS \ @@ -400,7 +386,6 @@ struct readahead_control; { IOCB_WAITQ, "WAITQ" }, \ { IOCB_NOIO, "NOIO" }, \ { IOCB_ALLOC_CACHE, "ALLOC_CACHE" }, \ - { IOCB_DIO_CALLER_COMP, "CALLER_COMP" }, \ { IOCB_AIO_RW, "AIO_RW" }, \ { IOCB_HAS_METADATA, "AIO_HAS_METADATA" } @@ -412,23 +397,13 @@ struct kiocb { int ki_flags; u16 ki_ioprio; /* See linux/ioprio.h */ u8 ki_write_stream; - union { - /* - * Only used for async buffered reads, where it denotes the - * page waitqueue associated with completing the read. Valid - * IFF IOCB_WAITQ is set. - */ - struct wait_page_queue *ki_waitq; - /* - * Can be used for O_DIRECT IO, where the completion handling - * is punted back to the issuer of the IO. May only be set - * if IOCB_DIO_CALLER_COMP is set by the issuer, and the issuer - * must then check for presence of this handler when ki_complete - * is invoked. The data passed in to this handler must be - * assigned to ->private when dio_complete is assigned. - */ - ssize_t (*dio_complete)(void *data); - }; + + /* + * Only used for async buffered reads, where it denotes the page + * waitqueue associated with completing the read. + * Valid IFF IOCB_WAITQ is set. + */ + struct wait_page_queue *ki_waitq; }; static inline bool is_sync_kiocb(struct kiocb *kiocb) diff --git a/io_uring/rw.c b/io_uring/rw.c index 08882648d569..4d0ab8f50d14 100644 --- a/io_uring/rw.c +++ b/io_uring/rw.c @@ -277,7 +277,6 @@ static int __io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe, } else { rw->kiocb.ki_ioprio = get_current_ioprio(); } - rw->kiocb.dio_complete = NULL; rw->kiocb.ki_flags = 0; rw->kiocb.ki_write_stream = READ_ONCE(sqe->write_stream); @@ -566,15 +565,6 @@ static inline int io_fixup_rw_res(struct io_kiocb *req, long res) void io_req_rw_complete(struct io_kiocb *req, io_tw_token_t tw) { - struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); - struct kiocb *kiocb = &rw->kiocb; - - if ((kiocb->ki_flags & IOCB_DIO_CALLER_COMP) && kiocb->dio_complete) { - long res = kiocb->dio_complete(rw->kiocb.private); - - io_req_set_res(req, io_fixup_rw_res(req, res), 0); - } - io_req_io_end(req); if (req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING)) @@ -589,10 +579,8 @@ static void io_complete_rw(struct kiocb *kiocb, long res) struct io_rw *rw = container_of(kiocb, struct io_rw, kiocb); struct io_kiocb *req = cmd_to_io_kiocb(rw); - if (!kiocb->dio_complete || !(kiocb->ki_flags & IOCB_DIO_CALLER_COMP)) { - __io_complete_rw_common(req, res); - io_req_set_res(req, io_fixup_rw_res(req, res), 0); - } + __io_complete_rw_common(req, res); + io_req_set_res(req, io_fixup_rw_res(req, res), 0); req->io_task_work.func = io_req_rw_complete; __io_req_task_work_add(req, IOU_F_TWQ_LAZY_WAKE); } |