diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c index 3a9b7a1b8704..598b259fda04 100644 --- a/fs/xfs/xfs_aops.c +++ b/fs/xfs/xfs_aops.c @@ -1233,6 +1233,117 @@ xfs_vm_releasepage( return try_to_free_buffers(page); } +/* + * When we map a DIO buffer, we may need to attach an ioend that describes the + * type of write IO we are doing. This passes to the completion function the + * operations it needs to perform. If the mapping is for an overwrite wholly + * within the EOF then we don't need an ioend and so we don't allocate one. + * This avoids the unnecessary overhead of allocating and freeing ioends for + * workloads that don't require transactions on IO completion. + * + * If we get multiple mappings in a single IO, we might be mapping different + * types. But because the direct IO can only have a single private pointer, we + * need to ensure that: + * + * a) i) the ioend spans the entire region of unwritten mappings; or + * ii) the ioend spans all the mappings that cross or are beyond EOF; and + * b) if it contains unwritten extents, it is *permanently* marked as such + * + * We could do this by chaining ioends like buffered IO does, but we only + * actually get one IO completion callback from the direct IO, and that spans + * the entire IO regardless of how many mappings and IOs are needed to complete + * the DIO. There is only going to be one reference to the ioend and its life + * cycle is constrained by the DIO completion code. hence we don't need + * reference counting here. + */ +static void +xfs_map_direct( + struct inode *inode, + struct buffer_head *bh_result, + struct xfs_bmbt_irec *imap, + xfs_off_t offset) +{ + struct xfs_ioend *ioend; + xfs_off_t size = bh_result->b_size; + int type; + + if (ISUNWRITTEN(imap)) + type = XFS_IO_UNWRITTEN; + else + type = XFS_IO_OVERWRITE; + + trace_xfs_gbmap_direct(XFS_I(inode), offset, size, type, imap); + + if (bh_result->b_private) { + ioend = bh_result->b_private; + ASSERT(ioend->io_size > 0); + ASSERT(offset >= ioend->io_offset); + if (offset + size > ioend->io_offset + ioend->io_size) + ioend->io_size = offset - ioend->io_offset + size; + + if (type == XFS_IO_UNWRITTEN && type != ioend->io_type) + ioend->io_type = XFS_IO_UNWRITTEN; + + trace_xfs_gbmap_direct_update(XFS_I(inode), ioend->io_offset, + ioend->io_size, ioend->io_type, + imap); + } else if (type == XFS_IO_UNWRITTEN || + offset + size > i_size_read(inode)) { + ioend = xfs_alloc_ioend(inode, type); + ioend->io_offset = offset; + ioend->io_size = size; + + bh_result->b_private = ioend; + set_buffer_defer_completion(bh_result); + + trace_xfs_gbmap_direct_new(XFS_I(inode), offset, size, type, + imap); + } else { + trace_xfs_gbmap_direct_none(XFS_I(inode), offset, size, type, + imap); + } +} + +/* + * If this is O_DIRECT or the mpage code calling tell them how large the mapping + * is, so that we can avoid repeated get_blocks calls. + * + * If the mapping spans EOF, then we have to break the mapping up as the mapping + * for blocks beyond EOF must be marked new so that sub block regions can be + * correctly zeroed. We can't do this for mappings within EOF unless the mapping + * was just allocated or is unwritten, otherwise the callers would overwrite + * existing data with zeros. Hence we have to split the mapping into a range up + * to and including EOF, and a second mapping for beyond EOF. + */ +static void +xfs_map_trim_size( + struct inode *inode, + sector_t iblock, + struct buffer_head *bh_result, + struct xfs_bmbt_irec *imap, + xfs_off_t offset, + ssize_t size) +{ + xfs_off_t mapping_size; + + mapping_size = imap->br_startoff + imap->br_blockcount - iblock; + mapping_size <<= inode->i_blkbits; + + ASSERT(mapping_size > 0); + if (mapping_size > size) + mapping_size = size; + if (offset < i_size_read(inode) && + offset + mapping_size >= i_size_read(inode)) { + /* limit mapping to block that spans EOF */ + mapping_size = roundup_64(i_size_read(inode) - offset, + 1 << inode->i_blkbits); + } + if (mapping_size > LONG_MAX) + mapping_size = LONG_MAX; + + bh_result->b_size = mapping_size; +} + STATIC int __xfs_get_blocks( struct inode *inode, @@ -1321,31 +1432,37 @@ __xfs_get_blocks( xfs_iunlock(ip, lockmode); } - - trace_xfs_get_blocks_alloc(ip, offset, size, 0, &imap); + trace_xfs_get_blocks_alloc(ip, offset, size, + ISUNWRITTEN(&imap) ? XFS_IO_UNWRITTEN + : XFS_IO_DELALLOC, &imap); } else if (nimaps) { - trace_xfs_get_blocks_found(ip, offset, size, 0, &imap); + trace_xfs_get_blocks_found(ip, offset, size, + ISUNWRITTEN(&imap) ? XFS_IO_UNWRITTEN + : XFS_IO_OVERWRITE, &imap); xfs_iunlock(ip, lockmode); } else { trace_xfs_get_blocks_notfound(ip, offset, size); goto out_unlock; } + /* trim mapping down to size requested */ + if (direct || size > (1 << inode->i_blkbits)) + xfs_map_trim_size(inode, iblock, bh_result, + &imap, offset, size); + + /* + * For unwritten extents do not report a disk address in the buffered + * read case (treat as if we're reading into a hole). + */ if (imap.br_startblock != HOLESTARTBLOCK && - imap.br_startblock != DELAYSTARTBLOCK) { - /* - * For unwritten extents do not report a disk address on - * the read case (treat as if we're reading into a hole). - */ - if (create || !ISUNWRITTEN(&imap)) - xfs_map_buffer(inode, bh_result, &imap, offset); - if (create && ISUNWRITTEN(&imap)) { - if (direct) { - bh_result->b_private = inode; - set_buffer_defer_completion(bh_result); - } + imap.br_startblock != DELAYSTARTBLOCK && + (create || !ISUNWRITTEN(&imap))) { + xfs_map_buffer(inode, bh_result, &imap, offset); + if (ISUNWRITTEN(&imap)) set_buffer_unwritten(bh_result); - } + /* direct IO needs special help */ + if (create && direct) + xfs_map_direct(inode, bh_result, &imap, offset); } /* @@ -1378,39 +1495,6 @@ __xfs_get_blocks( } } - /* - * If this is O_DIRECT or the mpage code calling tell them how large - * the mapping is, so that we can avoid repeated get_blocks calls. - * - * If the mapping spans EOF, then we have to break the mapping up as the - * mapping for blocks beyond EOF must be marked new so that sub block - * regions can be correctly zeroed. We can't do this for mappings within - * EOF unless the mapping was just allocated or is unwritten, otherwise - * the callers would overwrite existing data with zeros. Hence we have - * to split the mapping into a range up to and including EOF, and a - * second mapping for beyond EOF. - */ - if (direct || size > (1 << inode->i_blkbits)) { - xfs_off_t mapping_size; - - mapping_size = imap.br_startoff + imap.br_blockcount - iblock; - mapping_size <<= inode->i_blkbits; - - ASSERT(mapping_size > 0); - if (mapping_size > size) - mapping_size = size; - if (offset < i_size_read(inode) && - offset + mapping_size >= i_size_read(inode)) { - /* limit mapping to block that spans EOF */ - mapping_size = roundup_64(i_size_read(inode) - offset, - 1 << inode->i_blkbits); - } - if (mapping_size > LONG_MAX) - mapping_size = LONG_MAX; - - bh_result->b_size = mapping_size; - } - return 0; out_unlock: @@ -1441,9 +1525,11 @@ xfs_get_blocks_direct( /* * Complete a direct I/O write request. * - * If the private argument is non-NULL __xfs_get_blocks signals us that we - * need to issue a transaction to convert the range from unwritten to written - * extents. + * The ioend structure is passed from __xfs_get_blocks() to tell us what to do. + * If no ioend exists (i.e. @private == NULL) then the write IO is an overwrite + * wholly within the EOF and so there is nothing for us to do. Note that in this + * case the completion can be called in interrupt context, whereas if we have an + * ioend we will always be called in task context (i.e. from a workqueue). */ STATIC void xfs_end_io_direct_write( @@ -1455,43 +1541,71 @@ xfs_end_io_direct_write( struct inode *inode = file_inode(iocb->ki_filp); struct xfs_inode *ip = XFS_I(inode); struct xfs_mount *mp = ip->i_mount; + struct xfs_ioend *ioend = private; + + trace_xfs_gbmap_direct_endio(ip, offset, size, + ioend ? ioend->io_type : 0, NULL); + + if (!ioend) { + ASSERT(offset + size <= i_size_read(inode)); + return; + } if (XFS_FORCED_SHUTDOWN(mp)) - return; + goto out_end_io; /* - * While the generic direct I/O code updates the inode size, it does - * so only after the end_io handler is called, which means our - * end_io handler thinks the on-disk size is outside the in-core - * size. To prevent this just update it a little bit earlier here. + * dio completion end_io functions are only called on writes if more + * than 0 bytes was written. */ + ASSERT(size > 0); + + /* + * The ioend only maps whole blocks, while the IO may be sector aligned. + * Hence the ioend offset/size may not match the IO offset/size exactly. + * Because we don't map overwrites within EOF into the ioend, the offset + * may not match, but only if the endio spans EOF. Either way, write + * the IO sizes into the ioend so that completion processing does the + * right thing. + */ + ASSERT(offset + size <= ioend->io_offset + ioend->io_size); + ioend->io_size = size; + ioend->io_offset = offset; + + /* + * The ioend tells us whether we are doing unwritten extent conversion + * or an append transaction that updates the on-disk file size. These + * cases are the only cases where we should *potentially* be needing + * to update the VFS inode size. + * + * We need to update the in-core inode size here so that we don't end up + * with the on-disk inode size being outside the in-core inode size. We + * have no other method of updating EOF for AIO, so always do it here + * if necessary. + * + * We need to lock the test/set EOF update as we can be racing with + * other IO completions here to update the EOF. Failing to serialise + * here can result in EOF moving backwards and Bad Things Happen when + * that occurs. + */ + spin_lock(&ip->i_flags_lock); if (offset + size > i_size_read(inode)) i_size_write(inode, offset + size); + spin_unlock(&ip->i_flags_lock); /* - * For direct I/O we do not know if we need to allocate blocks or not, - * so we can't preallocate an append transaction, as that results in - * nested reservations and log space deadlocks. Hence allocate the - * transaction here. While this is sub-optimal and can block IO - * completion for some time, we're stuck with doing it this way until - * we can pass the ioend to the direct IO allocation callbacks and - * avoid nesting that way. + * If we are doing an append IO that needs to update the EOF on disk, + * do the transaction reserve now so we can use common end io + * processing. Stashing the error (if there is one) in the ioend will + * result in the ioend processing passing on the error if it is + * possible as we can't return it from here. */ - if (private && size > 0) { - xfs_iomap_write_unwritten(ip, offset, size); - } else if (offset + size > ip->i_d.di_size) { - struct xfs_trans *tp; - int error; + if (ioend->io_type == XFS_IO_OVERWRITE) + ioend->io_error = xfs_setfilesize_trans_alloc(ioend); - tp = xfs_trans_alloc(mp, XFS_TRANS_FSYNC_TS); - error = xfs_trans_reserve(tp, &M_RES(mp)->tr_fsyncts, 0, 0); - if (error) { - xfs_trans_cancel(tp, 0); - return; - } - - xfs_setfilesize(ip, tp, offset, size); - } +out_end_io: + xfs_end_io(&ioend->io_work); + return; } STATIC ssize_t diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index c203839cd5be..3a5d305e60c9 100644 --- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c @@ -569,20 +569,41 @@ restart: * write. If zeroing is needed and we are currently holding the * iolock shared, we need to update it to exclusive which implies * having to redo all checks before. + * + * We need to serialise against EOF updates that occur in IO + * completions here. We want to make sure that nobody is changing the + * size while we do this check until we have placed an IO barrier (i.e. + * hold the XFS_IOLOCK_EXCL) that prevents new IO from being dispatched. + * The spinlock effectively forms a memory barrier once we have the + * XFS_IOLOCK_EXCL so we are guaranteed to see the latest EOF value + * and hence be able to correctly determine if we need to run zeroing. */ + spin_lock(&ip->i_flags_lock); if (*pos > i_size_read(inode)) { bool zero = false; + spin_unlock(&ip->i_flags_lock); if (*iolock == XFS_IOLOCK_SHARED) { xfs_rw_iunlock(ip, *iolock); *iolock = XFS_IOLOCK_EXCL; xfs_rw_ilock(ip, *iolock); + + /* + * We now have an IO submission barrier in place, but + * AIO can do EOF updates during IO completion and hence + * we now need to wait for all of them to drain. Non-AIO + * DIO will have drained before we are given the + * XFS_IOLOCK_EXCL, and so for most cases this wait is a + * no-op. + */ + inode_dio_wait(inode); goto restart; } error = xfs_zero_eof(ip, *pos, i_size_read(inode), &zero); if (error) return error; - } + } else + spin_unlock(&ip->i_flags_lock); /* * Updating the timestamps will grab the ilock again from @@ -644,6 +665,8 @@ xfs_file_dio_aio_write( int iolock; size_t count = iov_iter_count(from); loff_t pos = iocb->ki_pos; + loff_t end; + struct iov_iter data; struct xfs_buftarg *target = XFS_IS_REALTIME_INODE(ip) ? mp->m_rtdev_targp : mp->m_ddev_targp; @@ -683,10 +706,11 @@ xfs_file_dio_aio_write( if (ret) goto out; iov_iter_truncate(from, count); + end = pos + count - 1; if (mapping->nrpages) { ret = filemap_write_and_wait_range(VFS_I(ip)->i_mapping, - pos, pos + count - 1); + pos, end); if (ret) goto out; /* @@ -696,7 +720,7 @@ xfs_file_dio_aio_write( */ ret = invalidate_inode_pages2_range(VFS_I(ip)->i_mapping, pos >> PAGE_CACHE_SHIFT, - (pos + count - 1) >> PAGE_CACHE_SHIFT); + end >> PAGE_CACHE_SHIFT); WARN_ON_ONCE(ret); ret = 0; } @@ -713,8 +737,22 @@ xfs_file_dio_aio_write( } trace_xfs_file_direct_write(ip, count, iocb->ki_pos, 0); - ret = generic_file_direct_write(iocb, from, pos); + data = *from; + ret = mapping->a_ops->direct_IO(WRITE, iocb, &data, pos); + + /* see generic_file_direct_write() for why this is necessary */ + if (mapping->nrpages) { + invalidate_inode_pages2_range(mapping, + pos >> PAGE_CACHE_SHIFT, + end >> PAGE_CACHE_SHIFT); + } + + if (ret > 0) { + pos += ret; + iov_iter_advance(from, ret); + iocb->ki_pos = pos; + } out: xfs_rw_iunlock(ip, iolock); diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h index b2a45cc9eceb..615781bf4ee5 100644 --- a/fs/xfs/xfs_trace.h +++ b/fs/xfs/xfs_trace.h @@ -1221,6 +1221,11 @@ DEFINE_IOMAP_EVENT(xfs_map_blocks_found); DEFINE_IOMAP_EVENT(xfs_map_blocks_alloc); DEFINE_IOMAP_EVENT(xfs_get_blocks_found); DEFINE_IOMAP_EVENT(xfs_get_blocks_alloc); +DEFINE_IOMAP_EVENT(xfs_gbmap_direct); +DEFINE_IOMAP_EVENT(xfs_gbmap_direct_new); +DEFINE_IOMAP_EVENT(xfs_gbmap_direct_update); +DEFINE_IOMAP_EVENT(xfs_gbmap_direct_none); +DEFINE_IOMAP_EVENT(xfs_gbmap_direct_endio); DECLARE_EVENT_CLASS(xfs_simple_io_class, TP_PROTO(struct xfs_inode *ip, xfs_off_t offset, ssize_t count),