/* * Copyright (c) 2000-2005 Silicon Graphics, Inc. * All Rights Reserved. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License as * published by the Free Software Foundation. * * This program is distributed in the hope that it would be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */ #include "xfs.h" #include "xfs_shared.h" #include "xfs_format.h" #include "xfs_log_format.h" #include "xfs_trans_resv.h" #include "xfs_mount.h" #include "xfs_inode.h" #include "xfs_trans.h" #include "xfs_inode_item.h" #include "xfs_alloc.h" #include "xfs_error.h" #include "xfs_iomap.h" #include "xfs_trace.h" #include "xfs_bmap.h" #include "xfs_bmap_util.h" #include "xfs_bmap_btree.h" #include "xfs_reflink.h" #include <linux/gfp.h> #include <linux/mpage.h> #include <linux/pagevec.h> #include <linux/writeback.h> /* * structure owned by writepages passed to individual writepage calls */ struct xfs_writepage_ctx { struct xfs_bmbt_irec imap; bool imap_valid; unsigned int io_type; struct xfs_ioend *ioend; sector_t last_block; }; void xfs_count_page_state( struct page *page, int *delalloc, int *unwritten) { struct buffer_head *bh, *head; *delalloc = *unwritten = 0; bh = head = page_buffers(page); do { if (buffer_unwritten(bh)) (*unwritten) = 1; else if (buffer_delay(bh)) (*delalloc) = 1; } while ((bh = bh->b_this_page) != head); } struct block_device * xfs_find_bdev_for_inode( struct inode *inode) { struct xfs_inode *ip = XFS_I(inode); struct xfs_mount *mp = ip->i_mount; if (XFS_IS_REALTIME_INODE(ip)) return mp->m_rtdev_targp->bt_bdev; else return mp->m_ddev_targp->bt_bdev; } /* * We're now finished for good with this page. Update the page state via the * associated buffer_heads, paying attention to the start and end offsets that * we need to process on the page. * * Landmine Warning: bh->b_end_io() will call end_page_writeback() on the last * buffer in the IO. Once it does this, it is unsafe to access the bufferhead or * the page at all, as we may be racing with memory reclaim and it can free both * the bufferhead chain and the page as it will see the page as clean and * unused. */ static void xfs_finish_page_writeback( struct inode *inode, struct bio_vec *bvec, int error) { unsigned int end = bvec->bv_offset + bvec->bv_len - 1; struct buffer_head *head, *bh, *next; unsigned int off = 0; unsigned int bsize; ASSERT(bvec->bv_offset < PAGE_SIZE); ASSERT((bvec->bv_offset & ((1 << inode->i_blkbits) - 1)) == 0); ASSERT(end < PAGE_SIZE); ASSERT((bvec->bv_len & ((1 << inode->i_blkbits) - 1)) == 0); bh = head = page_buffers(bvec->bv_page); bsize = bh->b_size; do { next = bh->b_this_page; if (off < bvec->bv_offset) goto next_bh; if (off > end) break; bh->b_end_io(bh, !error); next_bh: off += bsize; } while ((bh = next) != head); } /* * We're now finished for good with this ioend structure. Update the page * state, release holds on bios, and finally free up memory. Do not use the * ioend after this. */ STATIC void xfs_destroy_ioend( struct xfs_ioend *ioend, int error) { struct inode *inode = ioend->io_inode; struct bio *last = ioend->io_bio; struct bio *bio, *next; for (bio = &ioend->io_inline_bio; bio; bio = next) { struct bio_vec *bvec; int i; /* * For the last bio, bi_private points to the ioend, so we * need to explicitly end the iteration here. */ if (bio == last) next = NULL; else next = bio->bi_private; /* walk each page on bio, ending page IO on them */ bio_for_each_segment_all(bvec, bio, i) xfs_finish_page_writeback(inode, bvec, error); bio_put(bio); } } /* * Fast and loose check if this write could update the on-disk inode size. */ static inline bool xfs_ioend_is_append(struct xfs_ioend *ioend) { return ioend->io_offset + ioend->io_size > XFS_I(ioend->io_inode)->i_d.di_size; } STATIC int xfs_setfilesize_trans_alloc( struct xfs_ioend *ioend) { struct xfs_mount *mp = XFS_I(ioend->io_inode)->i_mount; struct xfs_trans *tp; int error; error = xfs_trans_alloc(mp, &M_RES(mp)->tr_fsyncts, 0, 0, 0, &tp); if (error) return error; ioend->io_append_trans = tp; /* * We may pass freeze protection with a transaction. So tell lockdep * we released it. */ __sb_writers_release(ioend->io_inode->i_sb, SB_FREEZE_FS); /* * We hand off the transaction to the completion thread now, so * clear the flag here. */ current_restore_flags_nested(&tp->t_pflags, PF_FSTRANS); return 0; } /* * Update on-disk file size now that data has been written to disk. */ STATIC int __xfs_setfilesize( struct xfs_inode *ip, struct xfs_trans *tp, xfs_off_t offset, size_t size) { xfs_fsize_t isize; xfs_ilock(ip, XFS_ILOCK_EXCL); isize = xfs_new_eof(ip, offset + size); if (!isize) { xfs_iunlock(ip, XFS_ILOCK_EXCL); xfs_trans_cancel(tp); return 0; } trace_xfs_setfilesize(ip, offset, size); ip->i_d.di_size = isize; xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL); xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE); return xfs_trans_commit(tp); } int xfs_setfilesize( struct xfs_inode *ip, xfs_off_t offset, size_t size) { struct xfs_mount *mp = ip->i_mount; struct xfs_trans *tp; int error; error = xfs_trans_alloc(mp, &M_RES(mp)->tr_fsyncts, 0, 0, 0, &tp); if (error) return error; return __xfs_setfilesize(ip, tp, offset, size); } STATIC int xfs_setfilesize_ioend( struct xfs_ioend *ioend, int error) { struct xfs_inode *ip = XFS_I(ioend->io_inode); struct xfs_trans *tp = ioend->io_append_trans; /* * The transaction may have been allocated in the I/O submission thread, * thus we need to mark ourselves as being in a transaction manually. * Similarly for freeze protection. */ current_set_flags_nested(&tp->t_pflags, PF_FSTRANS); __sb_writers_acquired(VFS_I(ip)->i_sb, SB_FREEZE_FS); /* we abort the update if there was an IO error */ if (error) { xfs_trans_cancel(tp); return error; } return __xfs_setfilesize(ip, tp, ioend->io_offset, ioend->io_size); } /* * IO write completion. */ STATIC void xfs_end_io( struct work_struct *work) { struct xfs_ioend *ioend = container_of(work, struct xfs_ioend, io_work); struct xfs_inode *ip = XFS_I(ioend->io_inode); int error = ioend->io_bio->bi_error; /* * Set an error if the mount has shut down and proceed with end I/O * processing so it can perform whatever cleanups are necessary. */ if (XFS_FORCED_SHUTDOWN(ip->i_mount)) error = -EIO; /* * For a CoW extent, we need to move the mapping from the CoW fork * to the data fork. If instead an error happened, just dump the * new blocks. */ if (ioend->io_type == XFS_IO_COW) { if (error) goto done; if (ioend->io_bio->bi_error) { error = xfs_reflink_cancel_cow_range(ip, ioend->io_offset, ioend->io_size); goto done; } error = xfs_reflink_end_cow(ip, ioend->io_offset, ioend->io_size); if (error) goto done; } /* * For unwritten extents we need to issue transactions to convert a * range to normal written extens after the data I/O has finished. * Detecting and handling completion IO errors is done individually * for each case as different cleanup operations need to be performed * on error. */ if (ioend->io_type == XFS_IO_UNWRITTEN) { if (error) goto done; error = xfs_iomap_write_unwritten(ip, ioend->io_offset, ioend->io_size); } else if (ioend->io_append_trans) { error = xfs_setfilesize_ioend(ioend, error); } else { ASSERT(!xfs_ioend_is_append(ioend) || ioend->io_type == XFS_IO_COW); } done: xfs_destroy_ioend(ioend, error); } STATIC void xfs_end_bio( struct bio *bio) { struct xfs_ioend *ioend = bio->bi_private; struct xfs_mount *mp = XFS_I(ioend->io_inode)->i_mount; if (ioend->io_type == XFS_IO_UNWRITTEN || ioend->io_type == XFS_IO_COW) queue_work(mp->m_unwritten_workqueue, &ioend->io_work); else if (ioend->io_append_trans) queue_work(mp->m_data_workqueue, &ioend->io_work); else xfs_destroy_ioend(ioend, bio->bi_error); } STATIC int xfs_map_blocks( struct inode *inode, loff_t offset, struct xfs_bmbt_irec *imap, int type) { struct xfs_inode *ip = XFS_I(inode); struct xfs_mount *mp = ip->i_mount; ssize_t count = 1 << inode->i_blkbits; xfs_fileoff_t offset_fsb, end_fsb; int error = 0; int bmapi_flags = XFS_BMAPI_ENTIRE; int nimaps = 1; if (XFS_FORCED_SHUTDOWN(mp)) return -EIO; ASSERT(type != XFS_IO_COW); if (type == XFS_IO_UNWRITTEN) bmapi_flags |= XFS_BMAPI_IGSTATE; xfs_ilock(ip, XFS_ILOCK_SHARED); ASSERT(ip->i_d.di_format != XFS_DINODE_FMT_BTREE || (ip->i_df.if_flags & XFS_IFEXTENTS)); ASSERT(offset <= mp->m_super->s_maxbytes); if (offset + count > mp->m_super->s_maxbytes) count = mp->m_super->s_maxbytes - offset; end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count); offset_fsb = XFS_B_TO_FSBT(mp, offset); error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb, imap, &nimaps, bmapi_flags); /* * Truncate an overwrite extent if there's a pending CoW * reservation before the end of this extent. This forces us * to come back to writepage to take care of the CoW. */ if (nimaps && type == XFS_IO_OVERWRITE) xfs_reflink_trim_irec_to_next_cow(ip, offset_fsb, imap); xfs_iunlock(ip, XFS_ILOCK_SHARED); if (error) return error; if (type == XFS_IO_DELALLOC && (!nimaps || isnullstartblock(imap->br_startblock))) { error = xfs_iomap_write_allocate(ip, XFS_DATA_FORK, offset, imap); if (!error) trace_xfs_map_blocks_alloc(ip, offset, count, type, imap); return error; } #ifdef DEBUG if (type == XFS_IO_UNWRITTEN) { ASSERT(nimaps); ASSERT(imap->br_startblock != HOLESTARTBLOCK); ASSERT(imap->br_startblock != DELAYSTARTBLOCK); } #endif if (nimaps) trace_xfs_map_blocks_found(ip, offset, count, type, imap); return 0; } STATIC bool xfs_imap_valid( struct inode *inode, struct xfs_bmbt_irec *imap, xfs_off_t offset) { offset >>= inode->i_blkbits; return offset >= imap->br_startoff && offset < imap->br_startoff + imap->br_blockcount; } STATIC void xfs_start_buffer_writeback( struct buffer_head *bh) { ASSERT(buffer_mapped(bh)); ASSERT(buffer_locked(bh)); ASSERT(!buffer_delay(bh)); ASSERT(!buffer_unwritten(bh)); mark_buffer_async_write(bh); set_buffer_uptodate(bh); clear_buffer_dirty(bh); } STATIC void xfs_start_page_writeback( struct page *page, int clear_dirty) { ASSERT(PageLocked(page)); ASSERT(!PageWriteback(page)); /* * if the page was not fully cleaned, we need to ensure that the higher * layers come back to it correctly. That means we need to keep the page * dirty, and for WB_SYNC_ALL writeback we need to ensure the * PAGECACHE_TAG_TOWRITE index mark is not removed so another attempt to * write this page in this writeback sweep will be made. */ if (clear_dirty) { clear_page_dirty_for_io(page); set_page_writeback(page); } else set_page_writeback_keepwrite(page); unlock_page(page); } static inline int xfs_bio_add_buffer(struct bio *bio, struct buffer_head *bh) { return bio_add_page(bio, bh->b_page, bh->b_size, bh_offset(bh)); } /* * Submit the bio for an ioend. We are passed an ioend with a bio attached to * it, and we submit that bio. The ioend may be used for multiple bio * submissions, so we only want to allocate an append transaction for the ioend * once. In the case of multiple bio submission, each bio will take an IO * reference to the ioend to ensure that the ioend completion is only done once * all bios have been submitted and the ioend is really done. * * If @fail is non-zero, it means that we have a situation where some part of * the submission process has failed after we have marked paged for writeback * and unlocked them. In this situation, we need to fail the bio and ioend * rather than submit it to IO. This typically only happens on a filesystem * shutdown. */ STATIC int xfs_submit_ioend( struct writeback_control *wbc, struct xfs_ioend *ioend, int status) { /* Reserve log space if we might write beyond the on-disk inode size. */ if (!status && ioend->io_type != XFS_IO_UNWRITTEN && xfs_ioend_is_append(ioend) && !ioend->io_append_trans) status = xfs_setfilesize_trans_alloc(ioend); ioend->io_bio->bi_private = ioend; ioend->io_bio->bi_end_io = xfs_end_bio; ioend->io_bio->bi_opf = REQ_OP_WRITE | wbc_to_write_flags(wbc); /* * If we are failing the IO now, just mark the ioend with an * error and finish it. This will run IO completion immediately * as there is only one reference to the ioend at this point in * time. */ if (status) { ioend->io_bio->bi_error = status; bio_endio(ioend->io_bio); return status; } submit_bio(ioend->io_bio); return 0; } static void xfs_init_bio_from_bh( struct bio *bio, struct buffer_head *bh) { bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9); bio->bi_bdev = bh->b_bdev; } static struct xfs_ioend * xfs_alloc_ioend( struct inode *inode, unsigned int type, xfs_off_t offset, struct buffer_head *bh) { struct xfs_ioend *ioend; struct bio *bio; bio = bio_alloc_bioset(GFP_NOFS, BIO_MAX_PAGES, xfs_ioend_bioset); xfs_init_bio_from_bh(bio, bh); ioend = container_of(bio, struct xfs_ioend, io_inline_bio); INIT_LIST_HEAD(&ioend->io_list); ioend->io_type = type; ioend->io_inode = inode; ioend->io_size = 0; ioend->io_offset = offset; INIT_WORK(&ioend->io_work, xfs_end_io); ioend->io_append_trans = NULL; ioend->io_bio = bio; return ioend; } /* * Allocate a new bio, and chain the old bio to the new one. * * Note that we have to do perform the chaining in this unintuitive order * so that the bi_private linkage is set up in the right direction for the * traversal in xfs_destroy_ioend(). */ static void xfs_chain_bio( struct xfs_ioend *ioend, struct writeback_control *wbc, struct buffer_head *bh) { struct bio *new; new = bio_alloc(GFP_NOFS, BIO_MAX_PAGES); xfs_init_bio_from_bh(new, bh); bio_chain(ioend->io_bio, new); bio_get(ioend->io_bio); /* for xfs_destroy_ioend */ ioend->io_bio->bi_opf = REQ_OP_WRITE | wbc_to_write_flags(wbc); submit_bio(ioend->io_bio); ioend->io_bio = new; } /* * Test to see if we've been building up a completion structure for * earlier buffers -- if so, we try to append to this ioend if we * can, otherwise we finish off any current ioend and start another. * Return the ioend we finished off so that the caller can submit it * once it has finished processing the dirty page. */ STATIC void xfs_add_to_ioend( struct inode *inode, struct buffer_head *bh, xfs_off_t offset, struct xfs_writepage_ctx *wpc, struct writeback_control *wbc, struct list_head *iolist) { if (!wpc->ioend || wpc->io_type != wpc->ioend->io_type || bh->b_blocknr != wpc->last_block + 1 || offset != wpc->ioend->io_offset + wpc->ioend->io_size) { if (wpc->ioend) list_add(&wpc->ioend->io_list, iolist); wpc->ioend = xfs_alloc_ioend(inode, wpc->io_type, offset, bh); } /* * If the buffer doesn't fit into the bio we need to allocate a new * one. This shouldn't happen more than once for a given buffer. */ while (xfs_bio_add_buffer(wpc->ioend->io_bio, bh) != bh->b_size) xfs_chain_bio(wpc->ioend, wbc, bh); wpc->ioend->io_size += bh->b_size; wpc->last_block = bh->b_blocknr; xfs_start_buffer_writeback(bh); } STATIC void xfs_map_buffer( struct inode *inode, struct buffer_head *bh, struct xfs_bmbt_irec *imap, xfs_off_t offset) { sector_t bn; struct xfs_mount *m = XFS_I(inode)->i_mount; xfs_off_t iomap_offset = XFS_FSB_TO_B(m, imap->br_startoff); xfs_daddr_t iomap_bn = xfs_fsb_to_db(XFS_I(inode), imap->br_startblock); ASSERT(imap->br_startblock != HOLESTARTBLOCK); ASSERT(imap->br_startblock != DELAYSTARTBLOCK); bn = (iomap_bn >> (inode->i_blkbits - BBSHIFT)) + ((offset - iomap_offset) >> inode->i_blkbits); ASSERT(bn || XFS_IS_REALTIME_INODE(XFS_I(inode))); bh->b_blocknr = bn; set_buffer_mapped(bh); } STATIC void xfs_map_at_offset( struct inode *inode, struct buffer_head *bh, struct xfs_bmbt_irec *imap, xfs_off_t offset) { ASSERT(imap->br_startblock != HOLESTARTBLOCK); ASSERT(imap->br_startblock != DELAYSTARTBLOCK); xfs_map_buffer(inode, bh, imap, offset); set_buffer_mapped(bh); clear_buffer_delay(bh); clear_buffer_unwritten(bh); } /* * Test if a given page contains at least one buffer of a given @type. * If @check_all_buffers is true, then we walk all the buffers in the page to * try to find one of the type passed in. If it is not set, then the caller only * needs to check the first buffer on the page for a match. */ STATIC bool xfs_check_page_type( struct page *page, unsigned int type, bool check_all_buffers) { struct buffer_head *bh; struct buffer_head *head; if (PageWriteback(page)) return false; if (!page->mapping) return false; if (!page_has_buffers(page)) return false; bh = head = page_buffers(page); do { if (buffer_unwritten(bh)) { if (type == XFS_IO_UNWRITTEN) return true; } else if (buffer_delay(bh)) { if (type == XFS_IO_DELALLOC) return true; } else if (buffer_dirty(bh) && buffer_mapped(bh)) { if (type == XFS_IO_OVERWRITE) return true; } /* If we are only checking the first buffer, we are done now. */ if (!check_all_buffers) break; } while ((bh = bh->b_this_page) != head); return false; } STATIC void xfs_vm_invalidatepage( struct page *page, unsigned int offset, unsigned int length) { trace_xfs_invalidatepage(page->mapping->host, page, offset, length); block_invalidatepage(page, offset, length); } /* * If the page has delalloc buffers on it, we need to punch them out before we * invalidate the page. If we don't, we leave a stale delalloc mapping on the * inode that can trip a BUG() in xfs_get_blocks() later on if a direct IO read * is done on that same region - the delalloc extent is returned when none is * supposed to be there. * * We prevent this by truncating away the delalloc regions on the page before * invalidating it. Because they are delalloc, we can do this without needing a * transaction. Indeed - if we get ENOSPC errors, we have to be able to do this * truncation without a transaction as there is no space left for block * reservation (typically why we see a ENOSPC in writeback). * * This is not a performance critical path, so for now just do the punching a * buffer head at a time. */ STATIC void xfs_aops_discard_page( struct page *page) { struct inode *inode = page->mapping->host; struct xfs_inode *ip = XFS_I(inode); struct buffer_head *bh, *head; loff_t offset = page_offset(page); if (!xfs_check_page_type(page, XFS_IO_DELALLOC, true)) goto out_invalidate; if (XFS_FORCED_SHUTDOWN(ip->i_mount)) goto out_invalidate; xfs_alert(ip->i_mount, "page discard on page %p, inode 0x%llx, offset %llu.", page, ip->i_ino, offset); xfs_ilock(ip, XFS_ILOCK_EXCL); bh = head = page_buffers(page); do { int error; xfs_fileoff_t start_fsb; if (!buffer_delay(bh)) goto next_buffer; start_fsb = XFS_B_TO_FSBT(ip->i_mount, offset); error = xfs_bmap_punch_delalloc_range(ip, start_fsb, 1); if (error) { /* something screwed, just bail */ if (!XFS_FORCED_SHUTDOWN(ip->i_mount)) { xfs_alert(ip->i_mount, "page discard unable to remove delalloc mapping."); } break; } next_buffer: offset += 1 << inode->i_blkbits; } while ((bh = bh->b_this_page) != head); xfs_iunlock(ip, XFS_ILOCK_EXCL); out_invalidate: xfs_vm_invalidatepage(page, 0, PAGE_SIZE); return; } static int xfs_map_cow( struct xfs_writepage_ctx *wpc, struct inode *inode, loff_t offset, unsigned int *new_type) { struct xfs_inode *ip = XFS_I(inode); struct xfs_bmbt_irec imap; bool is_cow = false; int error; /* * If we already have a valid COW mapping keep using it. */ if (wpc->io_type == XFS_IO_COW) { wpc->imap_valid = xfs_imap_valid(inode, &wpc->imap, offset); if (wpc->imap_valid) { *new_type = XFS_IO_COW; return 0; } } /* * Else we need to check if there is a COW mapping at this offset. */ xfs_ilock(ip, XFS_ILOCK_SHARED); is_cow = xfs_reflink_find_cow_mapping(ip, offset, &imap); xfs_iunlock(ip, XFS_ILOCK_SHARED); if (!is_cow) return 0; /* * And if the COW mapping has a delayed extent here we need to * allocate real space for it now. */ if (isnullstartblock(imap.br_startblock)) { error = xfs_iomap_write_allocate(ip, XFS_COW_FORK, offset, &imap); if (error) return error; } wpc->io_type = *new_type = XFS_IO_COW; wpc->imap_valid = true; wpc->imap = imap; return 0; } /* * We implement an immediate ioend submission policy here to avoid needing to * chain multiple ioends and hence nest mempool allocations which can violate * forward progress guarantees we need to provide. The current ioend we are * adding buffers to is cached on the writepage context, and if the new buffer * does not append to the cached ioend it will create a new ioend and cache that * instead. * * If a new ioend is created and cached, the old ioend is returned and queued * locally for submission once the entire page is processed or an error has been * detected. While ioends are submitted immediately after they are completed, * batching optimisations are provided by higher level block plugging. * * At the end of a writeback pass, there will be a cached ioend remaining on the * writepage context that the caller will need to submit. */ static int xfs_writepage_map( struct xfs_writepage_ctx *wpc, struct writeback_control *wbc, struct inode *inode, struct page *page, loff_t offset, __uint64_t end_offset) { LIST_HEAD(submit_list); struct xfs_ioend *ioend, *next; struct buffer_head *bh, *head; ssize_t len = 1 << inode->i_blkbits; int error = 0; int count = 0; int uptodate = 1; unsigned int new_type; bh = head = page_buffers(page); offset = page_offset(page); do { if (offset >= end_offset) break; if (!buffer_uptodate(bh)) uptodate = 0; /* * set_page_dirty dirties all buffers in a page, independent * of their state. The dirty state however is entirely * meaningless for holes (!mapped && uptodate), so skip * buffers covering holes here. */ if (!buffer_mapped(bh) && buffer_uptodate(bh)) { wpc->imap_valid = false; continue; } if (buffer_unwritten(bh)) new_type = XFS_IO_UNWRITTEN; else if (buffer_delay(bh)) new_type = XFS_IO_DELALLOC; else if (buffer_uptodate(bh)) new_type = XFS_IO_OVERWRITE; else { if (PageUptodate(page)) ASSERT(buffer_mapped(bh)); /* * This buffer is not uptodate and will not be * written to disk. Ensure that we will put any * subsequent writeable buffers into a new * ioend. */ wpc->imap_valid = false; continue; } if (xfs_is_reflink_inode(XFS_I(inode))) { error = xfs_map_cow(wpc, inode, offset, &new_type); if (error) goto out; } if (wpc->io_type != new_type) { wpc->io_type = new_type; wpc->imap_valid = false; } if (wpc->imap_valid) wpc->imap_valid = xfs_imap_valid(inode, &wpc->imap, offset); if (!wpc->imap_valid) { error = xfs_map_blocks(inode, offset, &wpc->imap, wpc->io_type); if (error) goto out; wpc->imap_valid = xfs_imap_valid(inode, &wpc->imap, offset); } if (wpc->imap_valid) { lock_buffer(bh); if (wpc->io_type != XFS_IO_OVERWRITE) xfs_map_at_offset(inode, bh, &wpc->imap, offset); xfs_add_to_ioend(inode, bh, offset, wpc, wbc, &submit_list); count++; } } while (offset += len, ((bh = bh->b_this_page) != head)); if (uptodate && bh == head) SetPageUptodate(page); ASSERT(wpc->ioend || list_empty(&submit_list)); out: /* * On error, we have to fail the ioend here because we have locked * buffers in the ioend. If we don't do this, we'll deadlock * invalidating the page as that tries to lock the buffers on the page. * Also, because we may have set pages under writeback, we have to make * sure we run IO completion to mark the error state of the IO * appropriately, so we can't cancel the ioend directly here. That means * we have to mark this page as under writeback if we included any * buffers from it in the ioend chain so that completion treats it * correctly. * * If we didn't include the page in the ioend, the on error we can * simply discard and unlock it as there are no other users of the page * or it's buffers right now. The caller will still need to trigger * submission of outstanding ioends on the writepage context so they are * treated correctly on error. */ if (count) { xfs_start_page_writeback(page, !error); /* * Preserve the original error if there was one, otherwise catch * submission errors here and propagate into subsequent ioend * submissions. */ list_for_each_entry_safe(ioend, next, &submit_list, io_list) { int error2; list_del_init(&ioend->io_list); error2 = xfs_submit_ioend(wbc, ioend, error); if (error2 && !error) error = error2; } } else if (error) { xfs_aops_discard_page(page); ClearPageUptodate(page); unlock_page(page); } else { /* * We can end up here with no error and nothing to write if we * race with a partial page truncate on a sub-page block sized * filesystem. In that case we need to mark the page clean. */ xfs_start_page_writeback(page, 1); end_page_writeback(page); } mapping_set_error(page->mapping, error); return error; } /* * Write out a dirty page. * * For delalloc space on the page we need to allocate space and flush it. * For unwritten space on the page we need to start the conversion to * regular allocated space. * For any other dirty buffer heads on the page we should flush them. */ STATIC int xfs_do_writepage( struct page *page, struct writeback_control *wbc, void *data) { struct xfs_writepage_ctx *wpc = data; struct inode *inode = page->mapping->host; loff_t offset; __uint64_t end_offset; pgoff_t end_index; trace_xfs_writepage(inode, page, 0, 0); ASSERT(page_has_buffers(page)); /* * Refuse to write the page out if we are called from reclaim context. * * This avoids stack overflows when called from deeply used stacks in * random callers for direct reclaim or memcg reclaim. We explicitly * allow reclaim from kswapd as the stack usage there is relatively low. * * This should never happen except in the case of a VM regression so * warn about it. */ if (WARN_ON_ONCE((current->flags & (PF_MEMALLOC|PF_KSWAPD)) == PF_MEMALLOC)) goto redirty; /* * Given that we do not allow direct reclaim to call us, we should * never be called while in a filesystem transaction. */ if (WARN_ON_ONCE(current->flags & PF_FSTRANS)) goto redirty; /* * Is this page beyond the end of the file? * * The page index is less than the end_index, adjust the end_offset * to the highest offset that this page should represent. * ----------------------------------------------------- * | file mapping | <EOF> | * ----------------------------------------------------- * | Page ... | Page N-2 | Page N-1 | Page N | | * ^--------------------------------^----------|-------- * | desired writeback range | see else | * ---------------------------------^------------------| */ offset = i_size_read(inode); end_index = offset >> PAGE_SHIFT; if (page->index < end_index) end_offset = (xfs_off_t)(page->index + 1) << PAGE_SHIFT; else { /* * Check whether the page to write out is beyond or straddles * i_size or not. * ------------------------------------------------------- * | file mapping | <EOF> | * ------------------------------------------------------- * | Page ... | Page N-2 | Page N-1 | Page N | Beyond | * ^--------------------------------^-----------|--------- * | | Straddles | * ---------------------------------^-----------|--------| */ unsigned offset_into_page = offset & (PAGE_SIZE - 1); /* * Skip the page if it is fully outside i_size, e.g. due to a * truncate operation that is in progress. We must redirty the * page so that reclaim stops reclaiming it. Otherwise * xfs_vm_releasepage() is called on it and gets confused. * * Note that the end_index is unsigned long, it would overflow * if the given offset is greater than 16TB on 32-bit system * and if we do check the page is fully outside i_size or not * via "if (page->index >= end_index + 1)" as "end_index + 1" * will be evaluated to 0. Hence this page will be redirtied * and be written out repeatedly which would result in an * infinite loop, the user program that perform this operation * will hang. Instead, we can verify this situation by checking * if the page to write is totally beyond the i_size or if it's * offset is just equal to the EOF. */ if (page->index > end_index || (page->index == end_index && offset_into_page == 0)) goto redirty; /* * The page straddles i_size. It must be zeroed out on each * and every writepage invocation because it may be mmapped. * "A file is mapped in multiples of the page size. For a file * that is not a multiple of the page size, the remaining * memory is zeroed when mapped, and writes to that region are * not written out to the file." */ zero_user_segment(page, offset_into_page, PAGE_SIZE); /* Adjust the end_offset to the end of file */ end_offset = offset; } return xfs_writepage_map(wpc, wbc, inode, page, offset, end_offset); redirty: redirty_page_for_writepage(wbc, page); unlock_page(page); return 0; } STATIC int xfs_vm_writepage( struct page *page, struct writeback_control *wbc) { struct xfs_writepage_ctx wpc = { .io_type = XFS_IO_INVALID, }; int ret; ret = xfs_do_writepage(page, wbc, &wpc); if (wpc.ioend) ret = xfs_submit_ioend(wbc, wpc.ioend, ret); return ret; } STATIC int xfs_vm_writepages( struct address_space *mapping, struct writeback_control *wbc) { struct xfs_writepage_ctx wpc = { .io_type = XFS_IO_INVALID, }; int ret; xfs_iflags_clear(XFS_I(mapping->host), XFS_ITRUNCATED); if (dax_mapping(mapping)) return dax_writeback_mapping_range(mapping, xfs_find_bdev_for_inode(mapping->host), wbc); ret = write_cache_pages(mapping, wbc, xfs_do_writepage, &wpc); if (wpc.ioend) ret = xfs_submit_ioend(wbc, wpc.ioend, ret); return ret; } /* * Called to move a page into cleanable state - and from there * to be released. The page should already be clean. We always * have buffer heads in this call. * * Returns 1 if the page is ok to release, 0 otherwise. */ STATIC int xfs_vm_releasepage( struct page *page, gfp_t gfp_mask) { int delalloc, unwritten; trace_xfs_releasepage(page->mapping->host, page, 0, 0); /* * mm accommodates an old ext3 case where clean pages might not have had * the dirty bit cleared. Thus, it can send actual dirty pages to * ->releasepage() via shrink_active_list(). Conversely, * block_invalidatepage() can send pages that are still marked dirty * but otherwise have invalidated buffers. * * We want to release the latter to avoid unnecessary buildup of the * LRU, skip the former and warn if we've left any lingering * delalloc/unwritten buffers on clean pages. Skip pages with delalloc * or unwritten buffers and warn if the page is not dirty. Otherwise * try to release the buffers. */ xfs_count_page_state(page, &delalloc, &unwritten); if (delalloc) { WARN_ON_ONCE(!PageDirty(page)); return 0; } if (unwritten) { WARN_ON_ONCE(!PageDirty(page)); return 0; } return try_to_free_buffers(page); } /* * 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, sector_t iblock, struct buffer_head *bh_result, int create) { struct xfs_inode *ip = XFS_I(inode); struct xfs_mount *mp = ip->i_mount; xfs_fileoff_t offset_fsb, end_fsb; int error = 0; int lockmode = 0; struct xfs_bmbt_irec imap; int nimaps = 1; xfs_off_t offset; ssize_t size; BUG_ON(create); if (XFS_FORCED_SHUTDOWN(mp)) return -EIO; offset = (xfs_off_t)iblock << inode->i_blkbits; ASSERT(bh_result->b_size >= (1 << inode->i_blkbits)); size = bh_result->b_size; if (offset >= i_size_read(inode)) return 0; /* * Direct I/O is usually done on preallocated files, so try getting * a block mapping without an exclusive lock first. */ lockmode = xfs_ilock_data_map_shared(ip); ASSERT(offset <= mp->m_super->s_maxbytes); if (offset + size > mp->m_super->s_maxbytes) size = mp->m_super->s_maxbytes - offset; end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + size); offset_fsb = XFS_B_TO_FSBT(mp, offset); error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb, &imap, &nimaps, XFS_BMAPI_ENTIRE); if (error) goto out_unlock; if (nimaps) { 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 */ 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 && !ISUNWRITTEN(&imap)) xfs_map_buffer(inode, bh_result, &imap, offset); /* * If this is a realtime file, data may be on a different device. * to that pointed to from the buffer_head b_bdev currently. */ bh_result->b_bdev = xfs_find_bdev_for_inode(inode); return 0; out_unlock: xfs_iunlock(ip, lockmode); return error; } STATIC ssize_t xfs_vm_direct_IO( struct kiocb *iocb, struct iov_iter *iter) { /* * We just need the method present so that open/fcntl allow direct I/O. */ return -EINVAL; } STATIC sector_t xfs_vm_bmap( struct address_space *mapping, sector_t block) { struct inode *inode = (struct inode *)mapping->host; struct xfs_inode *ip = XFS_I(inode); trace_xfs_vm_bmap(XFS_I(inode)); /* * The swap code (ab-)uses ->bmap to get a block mapping and then * bypasseѕ the file system for actual I/O. We really can't allow * that on reflinks inodes, so we have to skip out here. And yes, * 0 is the magic code for a bmap error.. */ if (xfs_is_reflink_inode(ip)) return 0; filemap_write_and_wait(mapping); return generic_block_bmap(mapping, block, xfs_get_blocks); } STATIC int xfs_vm_readpage( struct file *unused, struct page *page) { trace_xfs_vm_readpage(page->mapping->host, 1); return mpage_readpage(page, xfs_get_blocks); } STATIC int xfs_vm_readpages( struct file *unused, struct address_space *mapping, struct list_head *pages, unsigned nr_pages) { trace_xfs_vm_readpages(mapping->host, nr_pages); return mpage_readpages(mapping, pages, nr_pages, xfs_get_blocks); } /* * This is basically a copy of __set_page_dirty_buffers() with one * small tweak: buffers beyond EOF do not get marked dirty. If we mark them * dirty, we'll never be able to clean them because we don't write buffers * beyond EOF, and that means we can't invalidate pages that span EOF * that have been marked dirty. Further, the dirty state can leak into * the file interior if the file is extended, resulting in all sorts of * bad things happening as the state does not match the underlying data. * * XXX: this really indicates that bufferheads in XFS need to die. Warts like * this only exist because of bufferheads and how the generic code manages them. */ STATIC int xfs_vm_set_page_dirty( struct page *page) { struct address_space *mapping = page->mapping; struct inode *inode = mapping->host; loff_t end_offset; loff_t offset; int newly_dirty; if (unlikely(!mapping)) return !TestSetPageDirty(page); end_offset = i_size_read(inode); offset = page_offset(page); spin_lock(&mapping->private_lock); if (page_has_buffers(page)) { struct buffer_head *head = page_buffers(page); struct buffer_head *bh = head; do { if (offset < end_offset) set_buffer_dirty(bh); bh = bh->b_this_page; offset += 1 << inode->i_blkbits; } while (bh != head); } /* * Lock out page->mem_cgroup migration to keep PageDirty * synchronized with per-memcg dirty page counters. */ lock_page_memcg(page); newly_dirty = !TestSetPageDirty(page); spin_unlock(&mapping->private_lock); if (newly_dirty) { /* sigh - __set_page_dirty() is static, so copy it here, too */ unsigned long flags; spin_lock_irqsave(&mapping->tree_lock, flags); if (page->mapping) { /* Race with truncate? */ WARN_ON_ONCE(!PageUptodate(page)); account_page_dirtied(page, mapping); radix_tree_tag_set(&mapping->page_tree, page_index(page), PAGECACHE_TAG_DIRTY); } spin_unlock_irqrestore(&mapping->tree_lock, flags); } unlock_page_memcg(page); if (newly_dirty) __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); return newly_dirty; } const struct address_space_operations xfs_address_space_operations = { .readpage = xfs_vm_readpage, .readpages = xfs_vm_readpages, .writepage = xfs_vm_writepage, .writepages = xfs_vm_writepages, .set_page_dirty = xfs_vm_set_page_dirty, .releasepage = xfs_vm_releasepage, .invalidatepage = xfs_vm_invalidatepage, .bmap = xfs_vm_bmap, .direct_IO = xfs_vm_direct_IO, .migratepage = buffer_migrate_page, .is_partially_uptodate = block_is_partially_uptodate, .error_remove_page = generic_error_remove_page, };