--- /dev/null
+/*
+ * 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 <linux/gfp.h>
+#include <linux/mpage.h>
+#include <linux/pagevec.h>
+#include <linux/writeback.h>
+
+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);
+}
+
+STATIC 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 ioend structure.
+ * Update the page state via the associated buffer_heads,
+ * release holds on the inode and bio, and finally free
+ * up memory. Do not use the ioend after this.
+ */
+STATIC void
+xfs_destroy_ioend(
+ xfs_ioend_t *ioend)
+{
+ struct buffer_head *bh, *next;
+
+ for (bh = ioend->io_buffer_head; bh; bh = next) {
+ next = bh->b_private;
+ bh->b_end_io(bh, !ioend->io_error);
+ }
+
+ mempool_free(ioend, xfs_ioend_pool);
+}
+
+/*
+ * 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;
+
+ 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 error;
+ }
+
+ ioend->io_append_trans = tp;
+
+ /*
+ * We may pass freeze protection with a transaction. So tell lockdep
+ * we released it.
+ */
+ rwsem_release(&ioend->io_inode->i_sb->s_writers.lock_map[SB_FREEZE_FS-1],
+ 1, _THIS_IP_);
+ /*
+ * 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, 0);
+ 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, 0);
+}
+
+STATIC int
+xfs_setfilesize_ioend(
+ struct xfs_ioend *ioend)
+{
+ 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);
+ rwsem_acquire_read(&VFS_I(ip)->i_sb->s_writers.lock_map[SB_FREEZE_FS-1],
+ 0, 1, _THIS_IP_);
+
+ return xfs_setfilesize(ip, tp, ioend->io_offset, ioend->io_size);
+}
+
+/*
+ * Schedule IO completion handling on the final put of an ioend.
+ *
+ * If there is no work to do we might as well call it a day and free the
+ * ioend right now.
+ */
+STATIC void
+xfs_finish_ioend(
+ struct xfs_ioend *ioend)
+{
+ if (atomic_dec_and_test(&ioend->io_remaining)) {
+ struct xfs_mount *mp = XFS_I(ioend->io_inode)->i_mount;
+
+ if (ioend->io_type == XFS_IO_UNWRITTEN)
+ 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);
+ }
+}
+
+/*
+ * IO write completion.
+ */
+STATIC void
+xfs_end_io(
+ struct work_struct *work)
+{
+ xfs_ioend_t *ioend = container_of(work, xfs_ioend_t, io_work);
+ struct xfs_inode *ip = XFS_I(ioend->io_inode);
+ int error = 0;
+
+ if (XFS_FORCED_SHUTDOWN(ip->i_mount)) {
+ ioend->io_error = -EIO;
+ goto done;
+ }
+ if (ioend->io_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.
+ */
+ if (ioend->io_type == XFS_IO_UNWRITTEN) {
+ error = xfs_iomap_write_unwritten(ip, ioend->io_offset,
+ ioend->io_size);
+ } else if (ioend->io_append_trans) {
+ error = xfs_setfilesize_ioend(ioend);
+ } else {
+ ASSERT(!xfs_ioend_is_append(ioend));
+ }
+
+done:
+ if (error)
+ ioend->io_error = error;
+ xfs_destroy_ioend(ioend);
+}
+
+/*
+ * Allocate and initialise an IO completion structure.
+ * We need to track unwritten extent write completion here initially.
+ * We'll need to extend this for updating the ondisk inode size later
+ * (vs. incore size).
+ */
+STATIC xfs_ioend_t *
+xfs_alloc_ioend(
+ struct inode *inode,
+ unsigned int type)
+{
+ xfs_ioend_t *ioend;
+
+ ioend = mempool_alloc(xfs_ioend_pool, GFP_NOFS);
+
+ /*
+ * Set the count to 1 initially, which will prevent an I/O
+ * completion callback from happening before we have started
+ * all the I/O from calling the completion routine too early.
+ */
+ atomic_set(&ioend->io_remaining, 1);
+ ioend->io_error = 0;
+ ioend->io_list = NULL;
+ ioend->io_type = type;
+ ioend->io_inode = inode;
+ ioend->io_buffer_head = NULL;
+ ioend->io_buffer_tail = NULL;
+ ioend->io_offset = 0;
+ ioend->io_size = 0;
+ ioend->io_append_trans = NULL;
+
+ INIT_WORK(&ioend->io_work, xfs_end_io);
+ return ioend;
+}
+
+STATIC int
+xfs_map_blocks(
+ struct inode *inode,
+ loff_t offset,
+ struct xfs_bmbt_irec *imap,
+ int type,
+ int nonblocking)
+{
+ 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;
+
+ if (type == XFS_IO_UNWRITTEN)
+ bmapi_flags |= XFS_BMAPI_IGSTATE;
+
+ if (!xfs_ilock_nowait(ip, XFS_ILOCK_SHARED)) {
+ if (nonblocking)
+ return -EAGAIN;
+ 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);
+ 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, 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 int
+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;
+}
+
+/*
+ * BIO completion handler for buffered IO.
+ */
+STATIC void
+xfs_end_bio(
+ struct bio *bio,
+ int error)
+{
+ xfs_ioend_t *ioend = bio->bi_private;
+
+ ASSERT(atomic_read(&bio->bi_cnt) >= 1);
+ ioend->io_error = test_bit(BIO_UPTODATE, &bio->bi_flags) ? 0 : error;
+
+ /* Toss bio and pass work off to an xfsdatad thread */
+ bio->bi_private = NULL;
+ bio->bi_end_io = NULL;
+ bio_put(bio);
+
+ xfs_finish_ioend(ioend);
+}
+
+STATIC void
+xfs_submit_ioend_bio(
+ struct writeback_control *wbc,
+ xfs_ioend_t *ioend,
+ struct bio *bio)
+{
+ atomic_inc(&ioend->io_remaining);
+ bio->bi_private = ioend;
+ bio->bi_end_io = xfs_end_bio;
+ submit_bio(wbc->sync_mode == WB_SYNC_ALL ? WRITE_SYNC : WRITE, bio);
+}
+
+STATIC struct bio *
+xfs_alloc_ioend_bio(
+ struct buffer_head *bh)
+{
+ int nvecs = bio_get_nr_vecs(bh->b_bdev);
+ struct bio *bio = bio_alloc(GFP_NOIO, nvecs);
+
+ ASSERT(bio->bi_private == NULL);
+ bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9);
+ bio->bi_bdev = bh->b_bdev;
+ return bio;
+}
+
+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,
+ int buffers)
+{
+ 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);
+
+ /* If no buffers on the page are to be written, finish it here */
+ if (!buffers)
+ end_page_writeback(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 all of the bios for all of the ioends we have saved up, covering the
+ * initial writepage page and also any probed pages.
+ *
+ * Because we may have multiple ioends spanning a page, we need to start
+ * writeback on all the buffers before we submit them for I/O. If we mark the
+ * buffers as we got, then we can end up with a page that only has buffers
+ * marked async write and I/O complete on can occur before we mark the other
+ * buffers async write.
+ *
+ * The end result of this is that we trip a bug in end_page_writeback() because
+ * we call it twice for the one page as the code in end_buffer_async_write()
+ * assumes that all buffers on the page are started at the same time.
+ *
+ * The fix is two passes across the ioend list - one to start writeback on the
+ * buffer_heads, and then submit them for I/O on the second pass.
+ *
+ * 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 ioend chain rather
+ * than submit it to IO. This typically only happens on a filesystem shutdown.
+ */
+STATIC void
+xfs_submit_ioend(
+ struct writeback_control *wbc,
+ xfs_ioend_t *ioend,
+ int fail)
+{
+ xfs_ioend_t *head = ioend;
+ xfs_ioend_t *next;
+ struct buffer_head *bh;
+ struct bio *bio;
+ sector_t lastblock = 0;
+
+ /* Pass 1 - start writeback */
+ do {
+ next = ioend->io_list;
+ for (bh = ioend->io_buffer_head; bh; bh = bh->b_private)
+ xfs_start_buffer_writeback(bh);
+ } while ((ioend = next) != NULL);
+
+ /* Pass 2 - submit I/O */
+ ioend = head;
+ do {
+ next = ioend->io_list;
+ bio = NULL;
+
+ /*
+ * 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 (fail) {
+ ioend->io_error = fail;
+ xfs_finish_ioend(ioend);
+ continue;
+ }
+
+ for (bh = ioend->io_buffer_head; bh; bh = bh->b_private) {
+
+ if (!bio) {
+ retry:
+ bio = xfs_alloc_ioend_bio(bh);
+ } else if (bh->b_blocknr != lastblock + 1) {
+ xfs_submit_ioend_bio(wbc, ioend, bio);
+ goto retry;
+ }
+
+ if (xfs_bio_add_buffer(bio, bh) != bh->b_size) {
+ xfs_submit_ioend_bio(wbc, ioend, bio);
+ goto retry;
+ }
+
+ lastblock = bh->b_blocknr;
+ }
+ if (bio)
+ xfs_submit_ioend_bio(wbc, ioend, bio);
+ xfs_finish_ioend(ioend);
+ } while ((ioend = next) != NULL);
+}
+
+/*
+ * Cancel submission of all buffer_heads so far in this endio.
+ * Toss the endio too. Only ever called for the initial page
+ * in a writepage request, so only ever one page.
+ */
+STATIC void
+xfs_cancel_ioend(
+ xfs_ioend_t *ioend)
+{
+ xfs_ioend_t *next;
+ struct buffer_head *bh, *next_bh;
+
+ do {
+ next = ioend->io_list;
+ bh = ioend->io_buffer_head;
+ do {
+ next_bh = bh->b_private;
+ clear_buffer_async_write(bh);
+ /*
+ * The unwritten flag is cleared when added to the
+ * ioend. We're not submitting for I/O so mark the
+ * buffer unwritten again for next time around.
+ */
+ if (ioend->io_type == XFS_IO_UNWRITTEN)
+ set_buffer_unwritten(bh);
+ unlock_buffer(bh);
+ } while ((bh = next_bh) != NULL);
+
+ mempool_free(ioend, xfs_ioend_pool);
+ } while ((ioend = next) != NULL);
+}
+
+/*
+ * 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 true if we've finished the given ioend.
+ */
+STATIC void
+xfs_add_to_ioend(
+ struct inode *inode,
+ struct buffer_head *bh,
+ xfs_off_t offset,
+ unsigned int type,
+ xfs_ioend_t **result,
+ int need_ioend)
+{
+ xfs_ioend_t *ioend = *result;
+
+ if (!ioend || need_ioend || type != ioend->io_type) {
+ xfs_ioend_t *previous = *result;
+
+ ioend = xfs_alloc_ioend(inode, type);
+ ioend->io_offset = offset;
+ ioend->io_buffer_head = bh;
+ ioend->io_buffer_tail = bh;
+ if (previous)
+ previous->io_list = ioend;
+ *result = ioend;
+ } else {
+ ioend->io_buffer_tail->b_private = bh;
+ ioend->io_buffer_tail = bh;
+ }
+
+ bh->b_private = NULL;
+ ioend->io_size += bh->b_size;
+}
+
+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;
+}
+
+/*
+ * Allocate & map buffers for page given the extent map. Write it out.
+ * except for the original page of a writepage, this is called on
+ * delalloc/unwritten pages only, for the original page it is possible
+ * that the page has no mapping at all.
+ */
+STATIC int
+xfs_convert_page(
+ struct inode *inode,
+ struct page *page,
+ loff_t tindex,
+ struct xfs_bmbt_irec *imap,
+ xfs_ioend_t **ioendp,
+ struct writeback_control *wbc)
+{
+ struct buffer_head *bh, *head;
+ xfs_off_t end_offset;
+ unsigned long p_offset;
+ unsigned int type;
+ int len, page_dirty;
+ int count = 0, done = 0, uptodate = 1;
+ xfs_off_t offset = page_offset(page);
+
+ if (page->index != tindex)
+ goto fail;
+ if (!trylock_page(page))
+ goto fail;
+ if (PageWriteback(page))
+ goto fail_unlock_page;
+ if (page->mapping != inode->i_mapping)
+ goto fail_unlock_page;
+ if (!xfs_check_page_type(page, (*ioendp)->io_type, false))
+ goto fail_unlock_page;
+
+ /*
+ * page_dirty is initially a count of buffers on the page before
+ * EOF and is decremented as we move each into a cleanable state.
+ *
+ * Derivation:
+ *
+ * End offset is the highest offset that this page should represent.
+ * If we are on the last page, (end_offset & (PAGE_CACHE_SIZE - 1))
+ * will evaluate non-zero and be less than PAGE_CACHE_SIZE and
+ * hence give us the correct page_dirty count. On any other page,
+ * it will be zero and in that case we need page_dirty to be the
+ * count of buffers on the page.
+ */
+ end_offset = min_t(unsigned long long,
+ (xfs_off_t)(page->index + 1) << PAGE_CACHE_SHIFT,
+ i_size_read(inode));
+
+ /*
+ * If the current map does not span the entire page we are about to try
+ * to write, then give up. The only way we can write a page that spans
+ * multiple mappings in a single writeback iteration is via the
+ * xfs_vm_writepage() function. Data integrity writeback requires the
+ * entire page to be written in a single attempt, otherwise the part of
+ * the page we don't write here doesn't get written as part of the data
+ * integrity sync.
+ *
+ * For normal writeback, we also don't attempt to write partial pages
+ * here as it simply means that write_cache_pages() will see it under
+ * writeback and ignore the page until some point in the future, at
+ * which time this will be the only page in the file that needs
+ * writeback. Hence for more optimal IO patterns, we should always
+ * avoid partial page writeback due to multiple mappings on a page here.
+ */
+ if (!xfs_imap_valid(inode, imap, end_offset))
+ goto fail_unlock_page;
+
+ len = 1 << inode->i_blkbits;
+ p_offset = min_t(unsigned long, end_offset & (PAGE_CACHE_SIZE - 1),
+ PAGE_CACHE_SIZE);
+ p_offset = p_offset ? roundup(p_offset, len) : PAGE_CACHE_SIZE;
+ page_dirty = p_offset / len;
+
+ /*
+ * The moment we find a buffer that doesn't match our current type
+ * specification or can't be written, abort the loop and start
+ * writeback. As per the above xfs_imap_valid() check, only
+ * xfs_vm_writepage() can handle partial page writeback fully - we are
+ * limited here to the buffers that are contiguous with the current
+ * ioend, and hence a buffer we can't write breaks that contiguity and
+ * we have to defer the rest of the IO to xfs_vm_writepage().
+ */
+ bh = head = page_buffers(page);
+ do {
+ if (offset >= end_offset)
+ break;
+ if (!buffer_uptodate(bh))
+ uptodate = 0;
+ if (!(PageUptodate(page) || buffer_uptodate(bh))) {
+ done = 1;
+ break;
+ }
+
+ if (buffer_unwritten(bh) || buffer_delay(bh) ||
+ buffer_mapped(bh)) {
+ if (buffer_unwritten(bh))
+ type = XFS_IO_UNWRITTEN;
+ else if (buffer_delay(bh))
+ type = XFS_IO_DELALLOC;
+ else
+ type = XFS_IO_OVERWRITE;
+
+ /*
+ * imap should always be valid because of the above
+ * partial page end_offset check on the imap.
+ */
+ ASSERT(xfs_imap_valid(inode, imap, offset));
+
+ lock_buffer(bh);
+ if (type != XFS_IO_OVERWRITE)
+ xfs_map_at_offset(inode, bh, imap, offset);
+ xfs_add_to_ioend(inode, bh, offset, type,
+ ioendp, done);
+
+ page_dirty--;
+ count++;
+ } else {
+ done = 1;
+ break;
+ }
+ } while (offset += len, (bh = bh->b_this_page) != head);
+
+ if (uptodate && bh == head)
+ SetPageUptodate(page);
+
+ if (count) {
+ if (--wbc->nr_to_write <= 0 &&
+ wbc->sync_mode == WB_SYNC_NONE)
+ done = 1;
+ }
+ xfs_start_page_writeback(page, !page_dirty, count);
+
+ return done;
+ fail_unlock_page:
+ unlock_page(page);
+ fail:
+ return 1;
+}
+
+/*
+ * Convert & write out a cluster of pages in the same extent as defined
+ * by mp and following the start page.
+ */
+STATIC void
+xfs_cluster_write(
+ struct inode *inode,
+ pgoff_t tindex,
+ struct xfs_bmbt_irec *imap,
+ xfs_ioend_t **ioendp,
+ struct writeback_control *wbc,
+ pgoff_t tlast)
+{
+ struct pagevec pvec;
+ int done = 0, i;
+
+ pagevec_init(&pvec, 0);
+ while (!done && tindex <= tlast) {
+ unsigned len = min_t(pgoff_t, PAGEVEC_SIZE, tlast - tindex + 1);
+
+ if (!pagevec_lookup(&pvec, inode->i_mapping, tindex, len))
+ break;
+
+ for (i = 0; i < pagevec_count(&pvec); i++) {
+ done = xfs_convert_page(inode, pvec.pages[i], tindex++,
+ imap, ioendp, wbc);
+ if (done)
+ break;
+ }
+
+ pagevec_release(&pvec);
+ cond_resched();
+ }
+}
+
+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_CACHE_SIZE);
+ return;
+}
+
+/*
+ * 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_vm_writepage(
+ struct page *page,
+ struct writeback_control *wbc)
+{
+ struct inode *inode = page->mapping->host;
+ struct buffer_head *bh, *head;
+ struct xfs_bmbt_irec imap;
+ xfs_ioend_t *ioend = NULL, *iohead = NULL;
+ loff_t offset;
+ unsigned int type;
+ __uint64_t end_offset;
+ pgoff_t end_index, last_index;
+ ssize_t len;
+ int err, imap_valid = 0, uptodate = 1;
+ int count = 0;
+ int nonblocking = 0;
+
+ 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? */
+ offset = i_size_read(inode);
+ end_index = offset >> PAGE_CACHE_SHIFT;
+ last_index = (offset - 1) >> PAGE_CACHE_SHIFT;
+
+ /*
+ * 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 |
+ * ---------------------------------^------------------|
+ */
+ if (page->index < end_index)
+ end_offset = (xfs_off_t)(page->index + 1) << PAGE_CACHE_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_CACHE_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_CACHE_SIZE);
+
+ /* Adjust the end_offset to the end of file */
+ end_offset = offset;
+ }
+
+ len = 1 << inode->i_blkbits;
+
+ bh = head = page_buffers(page);
+ offset = page_offset(page);
+ type = XFS_IO_OVERWRITE;
+
+ if (wbc->sync_mode == WB_SYNC_NONE)
+ nonblocking = 1;
+
+ do {
+ int new_ioend = 0;
+
+ 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)) {
+ imap_valid = 0;
+ continue;
+ }
+
+ if (buffer_unwritten(bh)) {
+ if (type != XFS_IO_UNWRITTEN) {
+ type = XFS_IO_UNWRITTEN;
+ imap_valid = 0;
+ }
+ } else if (buffer_delay(bh)) {
+ if (type != XFS_IO_DELALLOC) {
+ type = XFS_IO_DELALLOC;
+ imap_valid = 0;
+ }
+ } else if (buffer_uptodate(bh)) {
+ if (type != XFS_IO_OVERWRITE) {
+ type = XFS_IO_OVERWRITE;
+ imap_valid = 0;
+ }
+ } 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.
+ */
+ imap_valid = 0;
+ continue;
+ }
+
+ if (imap_valid)
+ imap_valid = xfs_imap_valid(inode, &imap, offset);
+ if (!imap_valid) {
+ /*
+ * If we didn't have a valid mapping then we need to
+ * put the new mapping into a separate ioend structure.
+ * This ensures non-contiguous extents always have
+ * separate ioends, which is particularly important
+ * for unwritten extent conversion at I/O completion
+ * time.
+ */
+ new_ioend = 1;
+ err = xfs_map_blocks(inode, offset, &imap, type,
+ nonblocking);
+ if (err)
+ goto error;
+ imap_valid = xfs_imap_valid(inode, &imap, offset);
+ }
+ if (imap_valid) {
+ lock_buffer(bh);
+ if (type != XFS_IO_OVERWRITE)
+ xfs_map_at_offset(inode, bh, &imap, offset);
+ xfs_add_to_ioend(inode, bh, offset, type, &ioend,
+ new_ioend);
+ count++;
+ }
+
+ if (!iohead)
+ iohead = ioend;
+
+ } while (offset += len, ((bh = bh->b_this_page) != head));
+
+ if (uptodate && bh == head)
+ SetPageUptodate(page);
+
+ xfs_start_page_writeback(page, 1, count);
+
+ /* if there is no IO to be submitted for this page, we are done */
+ if (!ioend)
+ return 0;
+
+ ASSERT(iohead);
+
+ /*
+ * Any errors from this point onwards need tobe reported through the IO
+ * completion path as we have marked the initial page as under writeback
+ * and unlocked it.
+ */
+ if (imap_valid) {
+ xfs_off_t end_index;
+
+ end_index = imap.br_startoff + imap.br_blockcount;
+
+ /* to bytes */
+ end_index <<= inode->i_blkbits;
+
+ /* to pages */
+ end_index = (end_index - 1) >> PAGE_CACHE_SHIFT;
+
+ /* check against file size */
+ if (end_index > last_index)
+ end_index = last_index;
+
+ xfs_cluster_write(inode, page->index + 1, &imap, &ioend,
+ wbc, end_index);
+ }
+
+
+ /*
+ * Reserve log space if we might write beyond the on-disk inode size.
+ */
+ err = 0;
+ if (ioend->io_type != XFS_IO_UNWRITTEN && xfs_ioend_is_append(ioend))
+ err = xfs_setfilesize_trans_alloc(ioend);
+
+ xfs_submit_ioend(wbc, iohead, err);
+
+ return 0;
+
+error:
+ if (iohead)
+ xfs_cancel_ioend(iohead);
+
+ if (err == -EAGAIN)
+ goto redirty;
+
+ xfs_aops_discard_page(page);
+ ClearPageUptodate(page);
+ unlock_page(page);
+ return err;
+
+redirty:
+ redirty_page_for_writepage(wbc, page);
+ unlock_page(page);
+ return 0;
+}
+
+STATIC int
+xfs_vm_writepages(
+ struct address_space *mapping,
+ struct writeback_control *wbc)
+{
+ xfs_iflags_clear(XFS_I(mapping->host), XFS_ITRUNCATED);
+ return generic_writepages(mapping, wbc);
+}
+
+/*
+ * 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);
+
+ xfs_count_page_state(page, &delalloc, &unwritten);
+
+ if (WARN_ON_ONCE(delalloc))
+ return 0;
+ if (WARN_ON_ONCE(unwritten))
+ return 0;
+
+ 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,
+ sector_t iblock,
+ struct buffer_head *bh_result,
+ int create,
+ int direct)
+{
+ 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;
+ int new = 0;
+
+ 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 (!create && direct && 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. For buffered
+ * writes we already have the exclusive iolock anyway, so avoiding
+ * a lock roundtrip here by taking the ilock exclusive from the
+ * beginning is a useful micro optimization.
+ */
+ if (create && !direct) {
+ lockmode = XFS_ILOCK_EXCL;
+ xfs_ilock(ip, lockmode);
+ } else {
+ 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 (create &&
+ (!nimaps ||
+ (imap.br_startblock == HOLESTARTBLOCK ||
+ imap.br_startblock == DELAYSTARTBLOCK))) {
+ if (direct || xfs_get_extsz_hint(ip)) {
+ /*
+ * Drop the ilock in preparation for starting the block
+ * allocation transaction. It will be retaken
+ * exclusively inside xfs_iomap_write_direct for the
+ * actual allocation.
+ */
+ xfs_iunlock(ip, lockmode);
+ error = xfs_iomap_write_direct(ip, offset, size,
+ &imap, nimaps);
+ if (error)
+ return error;
+ new = 1;
+ } else {
+ /*
+ * Delalloc reservations do not require a transaction,
+ * we can go on without dropping the lock here. If we
+ * are allocating a new delalloc block, make sure that
+ * we set the new flag so that we mark the buffer new so
+ * that we know that it is newly allocated if the write
+ * fails.
+ */
+ if (nimaps && imap.br_startblock == HOLESTARTBLOCK)
+ new = 1;
+ error = xfs_iomap_write_delay(ip, offset, size, &imap);
+ if (error)
+ goto out_unlock;
+
+ xfs_iunlock(ip, lockmode);
+ }
+ 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,
+ 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 &&
+ (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);
+ }
+
+ /*
+ * 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);
+
+ /*
+ * If we previously allocated a block out beyond eof and we are now
+ * coming back to use it then we will need to flag it as new even if it
+ * has a disk address.
+ *
+ * With sub-block writes into unwritten extents we also need to mark
+ * the buffer as new so that the unwritten parts of the buffer gets
+ * correctly zeroed.
+ */
+ if (create &&
+ ((!buffer_mapped(bh_result) && !buffer_uptodate(bh_result)) ||
+ (offset >= i_size_read(inode)) ||
+ (new || ISUNWRITTEN(&imap))))
+ set_buffer_new(bh_result);
+
+ if (imap.br_startblock == DELAYSTARTBLOCK) {
+ BUG_ON(direct);
+ if (create) {
+ set_buffer_uptodate(bh_result);
+ set_buffer_mapped(bh_result);
+ set_buffer_delay(bh_result);
+ }
+ }
+
+ return 0;
+
+out_unlock:
+ xfs_iunlock(ip, lockmode);
+ return error;
+}
+
+int
+xfs_get_blocks(
+ struct inode *inode,
+ sector_t iblock,
+ struct buffer_head *bh_result,
+ int create)
+{
+ return __xfs_get_blocks(inode, iblock, bh_result, create, 0);
+}
+
+STATIC int
+xfs_get_blocks_direct(
+ struct inode *inode,
+ sector_t iblock,
+ struct buffer_head *bh_result,
+ int create)
+{
+ return __xfs_get_blocks(inode, iblock, bh_result, create, 1);
+}
+
+/*
+ * Complete a direct I/O write request.
+ *
+ * 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(
+ struct kiocb *iocb,
+ loff_t offset,
+ ssize_t size,
+ void *private)
+{
+ 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))
+ goto out_end_io;
+
+ /*
+ * 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);
+
+ /*
+ * 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 (ioend->io_type == XFS_IO_OVERWRITE)
+ ioend->io_error = xfs_setfilesize_trans_alloc(ioend);
+
+out_end_io:
+ xfs_end_io(&ioend->io_work);
+ return;
+}
+
+STATIC ssize_t
+xfs_vm_direct_IO(
+ struct kiocb *iocb,
+ struct iov_iter *iter,
+ loff_t offset)
+{
+ struct inode *inode = iocb->ki_filp->f_mapping->host;
+ struct block_device *bdev = xfs_find_bdev_for_inode(inode);
+
+ if (iov_iter_rw(iter) == WRITE) {
+ return __blockdev_direct_IO(iocb, inode, bdev, iter, offset,
+ xfs_get_blocks_direct,
+ xfs_end_io_direct_write, NULL,
+ DIO_ASYNC_EXTEND);
+ }
+ return __blockdev_direct_IO(iocb, inode, bdev, iter, offset,
+ xfs_get_blocks_direct, NULL, NULL, 0);
+}
+
+/*
+ * Punch out the delalloc blocks we have already allocated.
+ *
+ * Don't bother with xfs_setattr given that nothing can have made it to disk yet
+ * as the page is still locked at this point.
+ */
+STATIC void
+xfs_vm_kill_delalloc_range(
+ struct inode *inode,
+ loff_t start,
+ loff_t end)
+{
+ struct xfs_inode *ip = XFS_I(inode);
+ xfs_fileoff_t start_fsb;
+ xfs_fileoff_t end_fsb;
+ int error;
+
+ start_fsb = XFS_B_TO_FSB(ip->i_mount, start);
+ end_fsb = XFS_B_TO_FSB(ip->i_mount, end);
+ if (end_fsb <= start_fsb)
+ return;
+
+ xfs_ilock(ip, XFS_ILOCK_EXCL);
+ error = xfs_bmap_punch_delalloc_range(ip, start_fsb,
+ end_fsb - start_fsb);
+ if (error) {
+ /* something screwed, just bail */
+ if (!XFS_FORCED_SHUTDOWN(ip->i_mount)) {
+ xfs_alert(ip->i_mount,
+ "xfs_vm_write_failed: unable to clean up ino %lld",
+ ip->i_ino);
+ }
+ }
+ xfs_iunlock(ip, XFS_ILOCK_EXCL);
+}
+
+STATIC void
+xfs_vm_write_failed(
+ struct inode *inode,
+ struct page *page,
+ loff_t pos,
+ unsigned len)
+{
+ loff_t block_offset;
+ loff_t block_start;
+ loff_t block_end;
+ loff_t from = pos & (PAGE_CACHE_SIZE - 1);
+ loff_t to = from + len;
+ struct buffer_head *bh, *head;
+
+ /*
+ * The request pos offset might be 32 or 64 bit, this is all fine
+ * on 64-bit platform. However, for 64-bit pos request on 32-bit
+ * platform, the high 32-bit will be masked off if we evaluate the
+ * block_offset via (pos & PAGE_MASK) because the PAGE_MASK is
+ * 0xfffff000 as an unsigned long, hence the result is incorrect
+ * which could cause the following ASSERT failed in most cases.
+ * In order to avoid this, we can evaluate the block_offset of the
+ * start of the page by using shifts rather than masks the mismatch
+ * problem.
+ */
+ block_offset = (pos >> PAGE_CACHE_SHIFT) << PAGE_CACHE_SHIFT;
+
+ ASSERT(block_offset + from == pos);
+
+ head = page_buffers(page);
+ block_start = 0;
+ for (bh = head; bh != head || !block_start;
+ bh = bh->b_this_page, block_start = block_end,
+ block_offset += bh->b_size) {
+ block_end = block_start + bh->b_size;
+
+ /* skip buffers before the write */
+ if (block_end <= from)
+ continue;
+
+ /* if the buffer is after the write, we're done */
+ if (block_start >= to)
+ break;
+
+ if (!buffer_delay(bh))
+ continue;
+
+ if (!buffer_new(bh) && block_offset < i_size_read(inode))
+ continue;
+
+ xfs_vm_kill_delalloc_range(inode, block_offset,
+ block_offset + bh->b_size);
+
+ /*
+ * This buffer does not contain data anymore. make sure anyone
+ * who finds it knows that for certain.
+ */
+ clear_buffer_delay(bh);
+ clear_buffer_uptodate(bh);
+ clear_buffer_mapped(bh);
+ clear_buffer_new(bh);
+ clear_buffer_dirty(bh);
+ }
+
+}
+
+/*
+ * This used to call block_write_begin(), but it unlocks and releases the page
+ * on error, and we need that page to be able to punch stale delalloc blocks out
+ * on failure. hence we copy-n-waste it here and call xfs_vm_write_failed() at
+ * the appropriate point.
+ */
+STATIC int
+xfs_vm_write_begin(
+ struct file *file,
+ struct address_space *mapping,
+ loff_t pos,
+ unsigned len,
+ unsigned flags,
+ struct page **pagep,
+ void **fsdata)
+{
+ pgoff_t index = pos >> PAGE_CACHE_SHIFT;
+ struct page *page;
+ int status;
+
+ ASSERT(len <= PAGE_CACHE_SIZE);
+
+ page = grab_cache_page_write_begin(mapping, index, flags);
+ if (!page)
+ return -ENOMEM;
+
+ status = __block_write_begin(page, pos, len, xfs_get_blocks);
+ if (unlikely(status)) {
+ struct inode *inode = mapping->host;
+ size_t isize = i_size_read(inode);
+
+ xfs_vm_write_failed(inode, page, pos, len);
+ unlock_page(page);
+
+ /*
+ * If the write is beyond EOF, we only want to kill blocks
+ * allocated in this write, not blocks that were previously
+ * written successfully.
+ */
+ if (pos + len > isize) {
+ ssize_t start = max_t(ssize_t, pos, isize);
+
+ truncate_pagecache_range(inode, start, pos + len);
+ }
+
+ page_cache_release(page);
+ page = NULL;
+ }
+
+ *pagep = page;
+ return status;
+}
+
+/*
+ * On failure, we only need to kill delalloc blocks beyond EOF in the range of
+ * this specific write because they will never be written. Previous writes
+ * beyond EOF where block allocation succeeded do not need to be trashed, so
+ * only new blocks from this write should be trashed. For blocks within
+ * EOF, generic_write_end() zeros them so they are safe to leave alone and be
+ * written with all the other valid data.
+ */
+STATIC int
+xfs_vm_write_end(
+ struct file *file,
+ struct address_space *mapping,
+ loff_t pos,
+ unsigned len,
+ unsigned copied,
+ struct page *page,
+ void *fsdata)
+{
+ int ret;
+
+ ASSERT(len <= PAGE_CACHE_SIZE);
+
+ ret = generic_write_end(file, mapping, pos, len, copied, page, fsdata);
+ if (unlikely(ret < len)) {
+ struct inode *inode = mapping->host;
+ size_t isize = i_size_read(inode);
+ loff_t to = pos + len;
+
+ if (to > isize) {
+ /* only kill blocks in this write beyond EOF */
+ if (pos > isize)
+ isize = pos;
+ xfs_vm_kill_delalloc_range(inode, isize, to);
+ truncate_pagecache_range(inode, isize, to);
+ }
+ }
+ return ret;
+}
+
+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));
+ xfs_ilock(ip, XFS_IOLOCK_SHARED);
+ filemap_write_and_wait(mapping);
+ xfs_iunlock(ip, XFS_IOLOCK_SHARED);
+ return generic_block_bmap(mapping, block, xfs_get_blocks);
+}
+
+STATIC int
+xfs_vm_readpage(
+ struct file *unused,
+ struct page *page)
+{
+ 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)
+{
+ 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);
+ }
+ 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);
+ __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,
+ .write_begin = xfs_vm_write_begin,
+ .write_end = xfs_vm_write_end,
+ .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,
+};
Code Review / kvmfornfv.git / blobdiff