diff options
Diffstat (limited to 'fs/xfs/xfs_buf.c')
-rw-r--r-- | fs/xfs/xfs_buf.c | 353 |
1 files changed, 177 insertions, 176 deletions
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c index ec6505056b2c..017b6afe340b 100644 --- a/fs/xfs/xfs_buf.c +++ b/fs/xfs/xfs_buf.c @@ -623,10 +623,11 @@ _xfs_buf_read( bp->b_flags &= ~(XBF_WRITE | XBF_ASYNC | XBF_READ_AHEAD); bp->b_flags |= flags & (XBF_READ | XBF_ASYNC | XBF_READ_AHEAD); - xfs_buf_iorequest(bp); - if (flags & XBF_ASYNC) + if (flags & XBF_ASYNC) { + xfs_buf_submit(bp); return 0; - return xfs_buf_iowait(bp); + } + return xfs_buf_submit_wait(bp); } xfs_buf_t * @@ -687,34 +688,39 @@ xfs_buf_readahead_map( * Read an uncached buffer from disk. Allocates and returns a locked * buffer containing the disk contents or nothing. */ -struct xfs_buf * +int xfs_buf_read_uncached( struct xfs_buftarg *target, xfs_daddr_t daddr, size_t numblks, int flags, + struct xfs_buf **bpp, const struct xfs_buf_ops *ops) { struct xfs_buf *bp; + *bpp = NULL; + bp = xfs_buf_get_uncached(target, numblks, flags); if (!bp) - return NULL; + return -ENOMEM; /* set up the buffer for a read IO */ ASSERT(bp->b_map_count == 1); - bp->b_bn = daddr; + bp->b_bn = XFS_BUF_DADDR_NULL; /* always null for uncached buffers */ bp->b_maps[0].bm_bn = daddr; bp->b_flags |= XBF_READ; bp->b_ops = ops; - if (XFS_FORCED_SHUTDOWN(target->bt_mount)) { + xfs_buf_submit_wait(bp); + if (bp->b_error) { + int error = bp->b_error; xfs_buf_relse(bp); - return NULL; + return error; } - xfs_buf_iorequest(bp); - xfs_buf_iowait(bp); - return bp; + + *bpp = bp; + return 0; } /* @@ -998,53 +1004,56 @@ xfs_buf_wait_unpin( * Buffer Utility Routines */ -STATIC void -xfs_buf_iodone_work( - struct work_struct *work) +void +xfs_buf_ioend( + struct xfs_buf *bp) { - struct xfs_buf *bp = - container_of(work, xfs_buf_t, b_iodone_work); - bool read = !!(bp->b_flags & XBF_READ); + bool read = bp->b_flags & XBF_READ; + + trace_xfs_buf_iodone(bp, _RET_IP_); bp->b_flags &= ~(XBF_READ | XBF_WRITE | XBF_READ_AHEAD); - /* only validate buffers that were read without errors */ - if (read && bp->b_ops && !bp->b_error && (bp->b_flags & XBF_DONE)) + /* + * Pull in IO completion errors now. We are guaranteed to be running + * single threaded, so we don't need the lock to read b_io_error. + */ + if (!bp->b_error && bp->b_io_error) + xfs_buf_ioerror(bp, bp->b_io_error); + + /* Only validate buffers that were read without errors */ + if (read && !bp->b_error && bp->b_ops) { + ASSERT(!bp->b_iodone); bp->b_ops->verify_read(bp); + } + + if (!bp->b_error) + bp->b_flags |= XBF_DONE; if (bp->b_iodone) (*(bp->b_iodone))(bp); else if (bp->b_flags & XBF_ASYNC) xfs_buf_relse(bp); - else { - ASSERT(read && bp->b_ops); + else complete(&bp->b_iowait); - } } -void -xfs_buf_ioend( - struct xfs_buf *bp, - int schedule) +static void +xfs_buf_ioend_work( + struct work_struct *work) { - bool read = !!(bp->b_flags & XBF_READ); - - trace_xfs_buf_iodone(bp, _RET_IP_); + struct xfs_buf *bp = + container_of(work, xfs_buf_t, b_iodone_work); - if (bp->b_error == 0) - bp->b_flags |= XBF_DONE; + xfs_buf_ioend(bp); +} - if (bp->b_iodone || (read && bp->b_ops) || (bp->b_flags & XBF_ASYNC)) { - if (schedule) { - INIT_WORK(&bp->b_iodone_work, xfs_buf_iodone_work); - queue_work(xfslogd_workqueue, &bp->b_iodone_work); - } else { - xfs_buf_iodone_work(&bp->b_iodone_work); - } - } else { - bp->b_flags &= ~(XBF_READ | XBF_WRITE | XBF_READ_AHEAD); - complete(&bp->b_iowait); - } +void +xfs_buf_ioend_async( + struct xfs_buf *bp) +{ + INIT_WORK(&bp->b_iodone_work, xfs_buf_ioend_work); + queue_work(xfslogd_workqueue, &bp->b_iodone_work); } void @@ -1067,96 +1076,6 @@ xfs_buf_ioerror_alert( (__uint64_t)XFS_BUF_ADDR(bp), func, -bp->b_error, bp->b_length); } -/* - * Called when we want to stop a buffer from getting written or read. - * We attach the EIO error, muck with its flags, and call xfs_buf_ioend - * so that the proper iodone callbacks get called. - */ -STATIC int -xfs_bioerror( - xfs_buf_t *bp) -{ -#ifdef XFSERRORDEBUG - ASSERT(XFS_BUF_ISREAD(bp) || bp->b_iodone); -#endif - - /* - * No need to wait until the buffer is unpinned, we aren't flushing it. - */ - xfs_buf_ioerror(bp, -EIO); - - /* - * We're calling xfs_buf_ioend, so delete XBF_DONE flag. - */ - XFS_BUF_UNREAD(bp); - XFS_BUF_UNDONE(bp); - xfs_buf_stale(bp); - - xfs_buf_ioend(bp, 0); - - return -EIO; -} - -/* - * Same as xfs_bioerror, except that we are releasing the buffer - * here ourselves, and avoiding the xfs_buf_ioend call. - * This is meant for userdata errors; metadata bufs come with - * iodone functions attached, so that we can track down errors. - */ -int -xfs_bioerror_relse( - struct xfs_buf *bp) -{ - int64_t fl = bp->b_flags; - /* - * No need to wait until the buffer is unpinned. - * We aren't flushing it. - * - * chunkhold expects B_DONE to be set, whether - * we actually finish the I/O or not. We don't want to - * change that interface. - */ - XFS_BUF_UNREAD(bp); - XFS_BUF_DONE(bp); - xfs_buf_stale(bp); - bp->b_iodone = NULL; - if (!(fl & XBF_ASYNC)) { - /* - * Mark b_error and B_ERROR _both_. - * Lot's of chunkcache code assumes that. - * There's no reason to mark error for - * ASYNC buffers. - */ - xfs_buf_ioerror(bp, -EIO); - complete(&bp->b_iowait); - } else { - xfs_buf_relse(bp); - } - - return -EIO; -} - -STATIC int -xfs_bdstrat_cb( - struct xfs_buf *bp) -{ - if (XFS_FORCED_SHUTDOWN(bp->b_target->bt_mount)) { - trace_xfs_bdstrat_shut(bp, _RET_IP_); - /* - * Metadata write that didn't get logged but - * written delayed anyway. These aren't associated - * with a transaction, and can be ignored. - */ - if (!bp->b_iodone && !XFS_BUF_ISREAD(bp)) - return xfs_bioerror_relse(bp); - else - return xfs_bioerror(bp); - } - - xfs_buf_iorequest(bp); - return 0; -} - int xfs_bwrite( struct xfs_buf *bp) @@ -1166,11 +1085,10 @@ xfs_bwrite( ASSERT(xfs_buf_islocked(bp)); bp->b_flags |= XBF_WRITE; - bp->b_flags &= ~(XBF_ASYNC | XBF_READ | _XBF_DELWRI_Q | XBF_WRITE_FAIL); + bp->b_flags &= ~(XBF_ASYNC | XBF_READ | _XBF_DELWRI_Q | + XBF_WRITE_FAIL | XBF_DONE); - xfs_bdstrat_cb(bp); - - error = xfs_buf_iowait(bp); + error = xfs_buf_submit_wait(bp); if (error) { xfs_force_shutdown(bp->b_target->bt_mount, SHUTDOWN_META_IO_ERROR); @@ -1179,15 +1097,6 @@ xfs_bwrite( } STATIC void -_xfs_buf_ioend( - xfs_buf_t *bp, - int schedule) -{ - if (atomic_dec_and_test(&bp->b_io_remaining) == 1) - xfs_buf_ioend(bp, schedule); -} - -STATIC void xfs_buf_bio_end_io( struct bio *bio, int error) @@ -1198,13 +1107,18 @@ xfs_buf_bio_end_io( * don't overwrite existing errors - otherwise we can lose errors on * buffers that require multiple bios to complete. */ - if (!bp->b_error) - xfs_buf_ioerror(bp, error); + if (error) { + spin_lock(&bp->b_lock); + if (!bp->b_io_error) + bp->b_io_error = error; + spin_unlock(&bp->b_lock); + } if (!bp->b_error && xfs_buf_is_vmapped(bp) && (bp->b_flags & XBF_READ)) invalidate_kernel_vmap_range(bp->b_addr, xfs_buf_vmap_len(bp)); - _xfs_buf_ioend(bp, 1); + if (atomic_dec_and_test(&bp->b_io_remaining) == 1) + xfs_buf_ioend_async(bp); bio_put(bio); } @@ -1283,7 +1197,7 @@ next_chunk: } else { /* * This is guaranteed not to be the last io reference count - * because the caller (xfs_buf_iorequest) holds a count itself. + * because the caller (xfs_buf_submit) holds a count itself. */ atomic_dec(&bp->b_io_remaining); xfs_buf_ioerror(bp, -EIO); @@ -1373,53 +1287,131 @@ _xfs_buf_ioapply( blk_finish_plug(&plug); } +/* + * Asynchronous IO submission path. This transfers the buffer lock ownership and + * the current reference to the IO. It is not safe to reference the buffer after + * a call to this function unless the caller holds an additional reference + * itself. + */ void -xfs_buf_iorequest( - xfs_buf_t *bp) +xfs_buf_submit( + struct xfs_buf *bp) { - trace_xfs_buf_iorequest(bp, _RET_IP_); + trace_xfs_buf_submit(bp, _RET_IP_); ASSERT(!(bp->b_flags & _XBF_DELWRI_Q)); + ASSERT(bp->b_flags & XBF_ASYNC); + + /* on shutdown we stale and complete the buffer immediately */ + if (XFS_FORCED_SHUTDOWN(bp->b_target->bt_mount)) { + xfs_buf_ioerror(bp, -EIO); + bp->b_flags &= ~XBF_DONE; + xfs_buf_stale(bp); + xfs_buf_ioend(bp); + return; + } if (bp->b_flags & XBF_WRITE) xfs_buf_wait_unpin(bp); + + /* clear the internal error state to avoid spurious errors */ + bp->b_io_error = 0; + + /* + * The caller's reference is released during I/O completion. + * This occurs some time after the last b_io_remaining reference is + * released, so after we drop our Io reference we have to have some + * other reference to ensure the buffer doesn't go away from underneath + * us. Take a direct reference to ensure we have safe access to the + * buffer until we are finished with it. + */ xfs_buf_hold(bp); /* - * Set the count to 1 initially, this will stop an I/O - * completion callout which happens before we have started - * all the I/O from calling xfs_buf_ioend too early. + * Set the count to 1 initially, this will stop an I/O completion + * callout which happens before we have started all the I/O from calling + * xfs_buf_ioend too early. */ atomic_set(&bp->b_io_remaining, 1); _xfs_buf_ioapply(bp); + /* - * If _xfs_buf_ioapply failed, we'll get back here with - * only the reference we took above. _xfs_buf_ioend will - * drop it to zero, so we'd better not queue it for later, - * or we'll free it before it's done. + * If _xfs_buf_ioapply failed, we can get back here with only the IO + * reference we took above. If we drop it to zero, run completion so + * that we don't return to the caller with completion still pending. */ - _xfs_buf_ioend(bp, bp->b_error ? 0 : 1); + if (atomic_dec_and_test(&bp->b_io_remaining) == 1) { + if (bp->b_error) + xfs_buf_ioend(bp); + else + xfs_buf_ioend_async(bp); + } xfs_buf_rele(bp); + /* Note: it is not safe to reference bp now we've dropped our ref */ } /* - * Waits for I/O to complete on the buffer supplied. It returns immediately if - * no I/O is pending or there is already a pending error on the buffer, in which - * case nothing will ever complete. It returns the I/O error code, if any, or - * 0 if there was no error. + * Synchronous buffer IO submission path, read or write. */ int -xfs_buf_iowait( - xfs_buf_t *bp) +xfs_buf_submit_wait( + struct xfs_buf *bp) { - trace_xfs_buf_iowait(bp, _RET_IP_); + int error; - if (!bp->b_error) - wait_for_completion(&bp->b_iowait); + trace_xfs_buf_submit_wait(bp, _RET_IP_); + + ASSERT(!(bp->b_flags & (_XBF_DELWRI_Q | XBF_ASYNC))); + + if (XFS_FORCED_SHUTDOWN(bp->b_target->bt_mount)) { + xfs_buf_ioerror(bp, -EIO); + xfs_buf_stale(bp); + bp->b_flags &= ~XBF_DONE; + return -EIO; + } + + if (bp->b_flags & XBF_WRITE) + xfs_buf_wait_unpin(bp); + + /* clear the internal error state to avoid spurious errors */ + bp->b_io_error = 0; + + /* + * For synchronous IO, the IO does not inherit the submitters reference + * count, nor the buffer lock. Hence we cannot release the reference we + * are about to take until we've waited for all IO completion to occur, + * including any xfs_buf_ioend_async() work that may be pending. + */ + xfs_buf_hold(bp); + + /* + * Set the count to 1 initially, this will stop an I/O completion + * callout which happens before we have started all the I/O from calling + * xfs_buf_ioend too early. + */ + atomic_set(&bp->b_io_remaining, 1); + _xfs_buf_ioapply(bp); + + /* + * make sure we run completion synchronously if it raced with us and is + * already complete. + */ + if (atomic_dec_and_test(&bp->b_io_remaining) == 1) + xfs_buf_ioend(bp); + /* wait for completion before gathering the error from the buffer */ + trace_xfs_buf_iowait(bp, _RET_IP_); + wait_for_completion(&bp->b_iowait); trace_xfs_buf_iowait_done(bp, _RET_IP_); - return bp->b_error; + error = bp->b_error; + + /* + * all done now, we can release the hold that keeps the buffer + * referenced for the entire IO. + */ + xfs_buf_rele(bp); + return error; } xfs_caddr_t @@ -1813,13 +1805,19 @@ __xfs_buf_delwri_submit( blk_start_plug(&plug); list_for_each_entry_safe(bp, n, io_list, b_list) { bp->b_flags &= ~(_XBF_DELWRI_Q | XBF_ASYNC | XBF_WRITE_FAIL); - bp->b_flags |= XBF_WRITE; + bp->b_flags |= XBF_WRITE | XBF_ASYNC; - if (!wait) { - bp->b_flags |= XBF_ASYNC; + /* + * we do all Io submission async. This means if we need to wait + * for IO completion we need to take an extra reference so the + * buffer is still valid on the other side. + */ + if (wait) + xfs_buf_hold(bp); + else list_del_init(&bp->b_list); - } - xfs_bdstrat_cb(bp); + + xfs_buf_submit(bp); } blk_finish_plug(&plug); @@ -1866,7 +1864,10 @@ xfs_buf_delwri_submit( bp = list_first_entry(&io_list, struct xfs_buf, b_list); list_del_init(&bp->b_list); - error2 = xfs_buf_iowait(bp); + + /* locking the buffer will wait for async IO completion. */ + xfs_buf_lock(bp); + error2 = bp->b_error; xfs_buf_relse(bp); if (!error) error = error2; |