1 files changed, 172 insertions, 49 deletions

diff --git a/fs/xfs/linux-2.6/xfs_aops.c b/fs/xfs/linux-2.6/xfs_aops.c
index 66abe36c1213..9083357f9e44 100644
--- a/fs/xfs/linux-2.6/xfs_aops.c
+++ b/fs/xfs/linux-2.6/xfs_aops.c
@@ -39,6 +39,7 @@
 #include "xfs_iomap.h"
 #include "xfs_vnodeops.h"
 #include "xfs_trace.h"
+#include "xfs_bmap.h"
 #include <linux/mpage.h>
 #include <linux/pagevec.h>
 #include <linux/writeback.h>
@@ -163,14 +164,17 @@ xfs_ioend_new_eof(
 }
 
 /*
- * Update on-disk file size now that data has been written to disk.
- * The current in-memory file size is i_size.  If a write is beyond
- * eof i_new_size will be the intended file size until i_size is
- * updated.  If this write does not extend all the way to the valid
- * file size then restrict this update to the end of the write.
+ * Update on-disk file size now that data has been written to disk.  The
+ * current in-memory file size is i_size.  If a write is beyond eof i_new_size
+ * will be the intended file size until i_size is updated.  If this write does
+ * not extend all the way to the valid file size then restrict this update to
+ * the end of the write.
+ *
+ * This function does not block as blocking on the inode lock in IO completion
+ * can lead to IO completion order dependency deadlocks.. If it can't get the
+ * inode ilock it will return EAGAIN. Callers must handle this.
  */
-
-STATIC void
+STATIC int
 xfs_setfilesize(
         xfs_ioend_t             *ioend)
 {
@@ -181,16 +185,40 @@ xfs_setfilesize(
         ASSERT(ioend->io_type != IOMAP_READ);
 
         if (unlikely(ioend->io_error))
-                return;
+                return 0;
+
+        if (!xfs_ilock_nowait(ip, XFS_ILOCK_EXCL))
+                return EAGAIN;
 
-        xfs_ilock(ip, XFS_ILOCK_EXCL);
         isize = xfs_ioend_new_eof(ioend);
         if (isize) {
                 ip->i_d.di_size = isize;
-                xfs_mark_inode_dirty_sync(ip);
+                xfs_mark_inode_dirty(ip);
         }
 
         xfs_iunlock(ip, XFS_ILOCK_EXCL);
+        return 0;
+}
+
+/*
+ * Schedule IO completion handling on a xfsdatad if this was
+ * the final hold on this ioend. If we are asked to wait,
+ * flush the workqueue.
+ */
+STATIC void
+xfs_finish_ioend(
+        xfs_ioend_t     *ioend,
+        int             wait)
+{
+        if (atomic_dec_and_test(&ioend->io_remaining)) {
+                struct workqueue_struct *wq;
+
+                wq = (ioend->io_type == IOMAP_UNWRITTEN) ?
+                        xfsconvertd_workqueue : xfsdatad_workqueue;
+                queue_work(wq, &ioend->io_work);
+                if (wait)
+                        flush_workqueue(wq);
+        }
 }
 
 /*
@@ -198,11 +226,11 @@ xfs_setfilesize(
  */
 STATIC void
 xfs_end_io(
-        struct work_struct      *work)
+        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);
+        xfs_ioend_t     *ioend = container_of(work, xfs_ioend_t, io_work);
+        struct xfs_inode *ip = XFS_I(ioend->io_inode);
+        int             error = 0;
 
         /*
          * For unwritten extents we need to issue transactions to convert a
@@ -210,7 +238,6 @@ xfs_end_io(
          */
         if (ioend->io_type == IOMAP_UNWRITTEN &&
             likely(!ioend->io_error && !XFS_FORCED_SHUTDOWN(ip->i_mount))) {
-                int error;
 
                 error = xfs_iomap_write_unwritten(ip, ioend->io_offset,
                                                  ioend->io_size);
@@ -222,30 +249,23 @@ xfs_end_io(
          * We might have to update the on-disk file size after extending
          * writes.
          */
-        if (ioend->io_type != IOMAP_READ)
-                xfs_setfilesize(ioend);
-        xfs_destroy_ioend(ioend);
-}
-
-/*
- * Schedule IO completion handling on a xfsdatad if this was
- * the final hold on this ioend. If we are asked to wait,
- * flush the workqueue.
- */
-STATIC void
-xfs_finish_ioend(
-        xfs_ioend_t     *ioend,
-        int             wait)
-{
-        if (atomic_dec_and_test(&ioend->io_remaining)) {
-                struct workqueue_struct *wq;
-
-                wq = (ioend->io_type == IOMAP_UNWRITTEN) ?
-                        xfsconvertd_workqueue : xfsdatad_workqueue;
-                queue_work(wq, &ioend->io_work);
-                if (wait)
-                        flush_workqueue(wq);
+        if (ioend->io_type != IOMAP_READ) {
+                error = xfs_setfilesize(ioend);
+                ASSERT(!error || error == EAGAIN);
         }
+
+        /*
+         * If we didn't complete processing of the ioend, requeue it to the
+         * tail of the workqueue for another attempt later. Otherwise destroy
+         * it.
+         */
+        if (error == EAGAIN) {
+                atomic_inc(&ioend->io_remaining);
+                xfs_finish_ioend(ioend, 0);
+                /* ensure we don't spin on blocked ioends */
+                delay(1);
+        } else
+                xfs_destroy_ioend(ioend);
 }
 
 /*
@@ -341,7 +361,7 @@ xfs_submit_ioend_bio(
          * but don't update the inode size until I/O completion.
          */
         if (xfs_ioend_new_eof(ioend))
-                xfs_mark_inode_dirty_sync(XFS_I(ioend->io_inode));
+                xfs_mark_inode_dirty(XFS_I(ioend->io_inode));
 
         submit_bio(wbc->sync_mode == WB_SYNC_ALL ?
                    WRITE_SYNC_PLUG : WRITE, bio);
@@ -874,6 +894,118 @@ xfs_cluster_write(
         }
 }
 
+STATIC void
+xfs_vm_invalidatepage(
+        struct page             *page,
+        unsigned long           offset)
+{
+        trace_xfs_invalidatepage(page->mapping->host, page, offset);
+        block_invalidatepage(page, offset);
+}
+
+/*
+ * 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);
+        ssize_t                 len = 1 << inode->i_blkbits;
+
+        if (!xfs_is_delayed_page(page, IOMAP_DELAY))
+                goto out_invalidate;
+
+        xfs_fs_cmn_err(CE_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             done;
+                xfs_fileoff_t   offset_fsb;
+                xfs_bmbt_irec_t imap;
+                int             nimaps = 1;
+                int             error;
+                xfs_fsblock_t   firstblock;
+                xfs_bmap_free_t flist;
+
+                if (!buffer_delay(bh))
+                        goto next_buffer;
+
+                offset_fsb = XFS_B_TO_FSBT(ip->i_mount, offset);
+
+                /*
+                 * Map the range first and check that it is a delalloc extent
+                 * before trying to unmap the range. Otherwise we will be
+                 * trying to remove a real extent (which requires a
+                 * transaction) or a hole, which is probably a bad idea...
+                 */
+                error = xfs_bmapi(NULL, ip, offset_fsb, 1,
+                                XFS_BMAPI_ENTIRE,  NULL, 0, &imap,
+                                &nimaps, NULL, NULL);
+
+                if (error) {
+                        /* something screwed, just bail */
+                        xfs_fs_cmn_err(CE_ALERT, ip->i_mount,
+                        "page discard failed delalloc mapping lookup.");
+                        break;
+                }
+                if (!nimaps) {
+                        /* nothing there */
+                        goto next_buffer;
+                }
+                if (imap.br_startblock != DELAYSTARTBLOCK) {
+                        /* been converted, ignore */
+                        goto next_buffer;
+                }
+                WARN_ON(imap.br_blockcount == 0);
+
+                /*
+                 * Note: while we initialise the firstblock/flist pair, they
+                 * should never be used because blocks should never be
+                 * allocated or freed for a delalloc extent and hence we need
+                 * don't cancel or finish them after the xfs_bunmapi() call.
+                 */
+                xfs_bmap_init(&flist, &firstblock);
+                error = xfs_bunmapi(NULL, ip, offset_fsb, 1, 0, 1, &firstblock,
+                                        &flist, NULL, &done);
+
+                ASSERT(!flist.xbf_count && !flist.xbf_first);
+                if (error) {
+                        /* something screwed, just bail */
+                        xfs_fs_cmn_err(CE_ALERT, ip->i_mount,
+                        "page discard unable to remove delalloc mapping.");
+                        break;
+                }
+next_buffer:
+                offset += len;
+
+        } while ((bh = bh->b_this_page) != head);
+
+        xfs_iunlock(ip, XFS_ILOCK_EXCL);
+out_invalidate:
+        xfs_vm_invalidatepage(page, 0);
+        return;
+}
+
 /*
  * Calling this without startio set means we are being asked to make a dirty
  * page ready for freeing it's buffers.  When called with startio set then
@@ -1125,7 +1257,7 @@ error:
          */
         if (err != -EAGAIN) {
                 if (!unmapped)
-                        block_invalidatepage(page, 0);
+                        xfs_aops_discard_page(page);
                 ClearPageUptodate(page);
         }
         return err;
@@ -1535,15 +1667,6 @@ xfs_vm_readpages(
         return mpage_readpages(mapping, pages, nr_pages, xfs_get_blocks);
 }
 
-STATIC void
-xfs_vm_invalidatepage(
-        struct page             *page,
-        unsigned long           offset)
-{
-        trace_xfs_invalidatepage(page->mapping->host, page, offset);
-        block_invalidatepage(page, offset);
-}
-
 const struct address_space_operations xfs_address_space_operations = {
         .readpage               = xfs_vm_readpage,
         .readpages              = xfs_vm_readpages,