Merge branch 'linux-2.6'

1 files changed, 835 insertions, 0 deletions

diff --git a/fs/afs/write.c b/fs/afs/write.c
new file mode 100644
index 000000000000..83ff29262816
--- /dev/null
+++ b/fs/afs/write.c
@@ -0,0 +1,835 @@
+/* handling of writes to regular files and writing back to the server
+ *
+ * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * 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; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/slab.h>
+#include <linux/fs.h>
+#include <linux/pagemap.h>
+#include <linux/writeback.h>
+#include <linux/pagevec.h>
+#include "internal.h"
+
+static int afs_write_back_from_locked_page(struct afs_writeback *wb,
+                                           struct page *page);
+
+/*
+ * mark a page as having been made dirty and thus needing writeback
+ */
+int afs_set_page_dirty(struct page *page)
+{
+        _enter("");
+        return __set_page_dirty_nobuffers(page);
+}
+
+/*
+ * unlink a writeback record because its usage has reached zero
+ * - must be called with the wb->vnode->writeback_lock held
+ */
+static void afs_unlink_writeback(struct afs_writeback *wb)
+{
+        struct afs_writeback *front;
+        struct afs_vnode *vnode = wb->vnode;
+
+        list_del_init(&wb->link);
+        if (!list_empty(&vnode->writebacks)) {
+                /* if an fsync rises to the front of the queue then wake it
+                 * up */
+                front = list_entry(vnode->writebacks.next,
+                                   struct afs_writeback, link);
+                if (front->state == AFS_WBACK_SYNCING) {
+                        _debug("wake up sync");
+                        front->state = AFS_WBACK_COMPLETE;
+                        wake_up(&front->waitq);
+                }
+        }
+}
+
+/*
+ * free a writeback record
+ */
+static void afs_free_writeback(struct afs_writeback *wb)
+{
+        _enter("");
+        key_put(wb->key);
+        kfree(wb);
+}
+
+/*
+ * dispose of a reference to a writeback record
+ */
+void afs_put_writeback(struct afs_writeback *wb)
+{
+        struct afs_vnode *vnode = wb->vnode;
+
+        _enter("{%d}", wb->usage);
+
+        spin_lock(&vnode->writeback_lock);
+        if (--wb->usage == 0)
+                afs_unlink_writeback(wb);
+        else
+                wb = NULL;
+        spin_unlock(&vnode->writeback_lock);
+        if (wb)
+                afs_free_writeback(wb);
+}
+
+/*
+ * partly or wholly fill a page that's under preparation for writing
+ */
+static int afs_fill_page(struct afs_vnode *vnode, struct key *key,
+                         unsigned start, unsigned len, struct page *page)
+{
+        int ret;
+
+        _enter(",,%u,%u", start, len);
+
+        ASSERTCMP(start + len, <=, PAGE_SIZE);
+
+        ret = afs_vnode_fetch_data(vnode, key, start, len, page);
+        if (ret < 0) {
+                if (ret == -ENOENT) {
+                        _debug("got NOENT from server"
+                               " - marking file deleted and stale");
+                        set_bit(AFS_VNODE_DELETED, &vnode->flags);
+                        ret = -ESTALE;
+                }
+        }
+
+        _leave(" = %d", ret);
+        return ret;
+}
+
+/*
+ * prepare a page for being written to
+ */
+static int afs_prepare_page(struct afs_vnode *vnode, struct page *page,
+                            struct key *key, unsigned offset, unsigned to)
+{
+        unsigned eof, tail, start, stop, len;
+        loff_t i_size, pos;
+        void *p;
+        int ret;
+
+        _enter("");
+
+        if (offset == 0 && to == PAGE_SIZE)
+                return 0;
+
+        p = kmap(page);
+
+        i_size = i_size_read(&vnode->vfs_inode);
+        pos = (loff_t) page->index << PAGE_SHIFT;
+        if (pos >= i_size) {
+                /* partial write, page beyond EOF */
+                _debug("beyond");
+                if (offset > 0)
+                        memset(p, 0, offset);
+                if (to < PAGE_SIZE)
+                        memset(p + to, 0, PAGE_SIZE - to);
+                kunmap(page);
+                return 0;
+        }
+
+        if (i_size - pos >= PAGE_SIZE) {
+                /* partial write, page entirely before EOF */
+                _debug("before");
+                tail = eof = PAGE_SIZE;
+        } else {
+                /* partial write, page overlaps EOF */
+                eof = i_size - pos;
+                _debug("overlap %u", eof);
+                tail = max(eof, to);
+                if (tail < PAGE_SIZE)
+                        memset(p + tail, 0, PAGE_SIZE - tail);
+                if (offset > eof)
+                        memset(p + eof, 0, PAGE_SIZE - eof);
+        }
+
+        kunmap(p);
+
+        ret = 0;
+        if (offset > 0 || eof > to) {
+                /* need to fill one or two bits that aren't going to be written
+                 * (cover both fillers in one read if there are two) */
+                start = (offset > 0) ? 0 : to;
+                stop = (eof > to) ? eof : offset;
+                len = stop - start;
+                _debug("wr=%u-%u av=0-%u rd=%u@%u",
+                       offset, to, eof, start, len);
+                ret = afs_fill_page(vnode, key, start, len, page);
+        }
+
+        _leave(" = %d", ret);
+        return ret;
+}
+
+/*
+ * prepare to perform part of a write to a page
+ * - the caller holds the page locked, preventing it from being written out or
+ *   modified by anyone else
+ */
+int afs_prepare_write(struct file *file, struct page *page,
+                      unsigned offset, unsigned to)
+{
+        struct afs_writeback *candidate, *wb;
+        struct afs_vnode *vnode = AFS_FS_I(file->f_dentry->d_inode);
+        struct key *key = file->private_data;
+        pgoff_t index;
+        int ret;
+
+        _enter("{%x:%u},{%lx},%u,%u",
+               vnode->fid.vid, vnode->fid.vnode, page->index, offset, to);
+
+        candidate = kzalloc(sizeof(*candidate), GFP_KERNEL);
+        if (!candidate)
+                return -ENOMEM;
+        candidate->vnode = vnode;
+        candidate->first = candidate->last = page->index;
+        candidate->offset_first = offset;
+        candidate->to_last = to;
+        candidate->usage = 1;
+        candidate->state = AFS_WBACK_PENDING;
+        init_waitqueue_head(&candidate->waitq);
+
+        if (!PageUptodate(page)) {
+                _debug("not up to date");
+                ret = afs_prepare_page(vnode, page, key, offset, to);
+                if (ret < 0) {
+                        kfree(candidate);
+                        _leave(" = %d [prep]", ret);
+                        return ret;
+                }
+                SetPageUptodate(page);
+        }
+
+try_again:
+        index = page->index;
+        spin_lock(&vnode->writeback_lock);
+
+        /* see if this page is already pending a writeback under a suitable key
+         * - if so we can just join onto that one */
+        wb = (struct afs_writeback *) page_private(page);
+        if (wb) {
+                if (wb->key == key && wb->state == AFS_WBACK_PENDING)
+                        goto subsume_in_current_wb;
+                goto flush_conflicting_wb;
+        }
+
+        if (index > 0) {
+                /* see if we can find an already pending writeback that we can
+                 * append this page to */
+                list_for_each_entry(wb, &vnode->writebacks, link) {
+                        if (wb->last == index - 1 && wb->key == key &&
+                            wb->state == AFS_WBACK_PENDING)
+                                goto append_to_previous_wb;
+                }
+        }
+
+        list_add_tail(&candidate->link, &vnode->writebacks);
+        candidate->key = key_get(key);
+        spin_unlock(&vnode->writeback_lock);
+        SetPagePrivate(page);
+        set_page_private(page, (unsigned long) candidate);
+        _leave(" = 0 [new]");
+        return 0;
+
+subsume_in_current_wb:
+        _debug("subsume");
+        ASSERTRANGE(wb->first, <=, index, <=, wb->last);
+        if (index == wb->first && offset < wb->offset_first)
+                wb->offset_first = offset;
+        if (index == wb->last && to > wb->to_last)
+                wb->to_last = to;
+        spin_unlock(&vnode->writeback_lock);
+        kfree(candidate);
+        _leave(" = 0 [sub]");
+        return 0;
+
+append_to_previous_wb:
+        _debug("append into %lx-%lx", wb->first, wb->last);
+        wb->usage++;
+        wb->last++;
+        wb->to_last = to;
+        spin_unlock(&vnode->writeback_lock);
+        SetPagePrivate(page);
+        set_page_private(page, (unsigned long) wb);
+        kfree(candidate);
+        _leave(" = 0 [app]");
+        return 0;
+
+        /* the page is currently bound to another context, so if it's dirty we
+         * need to flush it before we can use the new context */
+flush_conflicting_wb:
+        _debug("flush conflict");
+        if (wb->state == AFS_WBACK_PENDING)
+                wb->state = AFS_WBACK_CONFLICTING;
+        spin_unlock(&vnode->writeback_lock);
+        if (PageDirty(page)) {
+                ret = afs_write_back_from_locked_page(wb, page);
+                if (ret < 0) {
+                        afs_put_writeback(candidate);
+                        _leave(" = %d", ret);
+                        return ret;
+                }
+        }
+
+        /* the page holds a ref on the writeback record */
+        afs_put_writeback(wb);
+        set_page_private(page, 0);
+        ClearPagePrivate(page);
+        goto try_again;
+}
+
+/*
+ * finalise part of a write to a page
+ */
+int afs_commit_write(struct file *file, struct page *page,
+                     unsigned offset, unsigned to)
+{
+        struct afs_vnode *vnode = AFS_FS_I(file->f_dentry->d_inode);
+        loff_t i_size, maybe_i_size;
+
+        _enter("{%x:%u},{%lx},%u,%u",
+               vnode->fid.vid, vnode->fid.vnode, page->index, offset, to);
+
+        maybe_i_size = (loff_t) page->index << PAGE_SHIFT;
+        maybe_i_size += to;
+
+        i_size = i_size_read(&vnode->vfs_inode);
+        if (maybe_i_size > i_size) {
+                spin_lock(&vnode->writeback_lock);
+                i_size = i_size_read(&vnode->vfs_inode);
+                if (maybe_i_size > i_size)
+                        i_size_write(&vnode->vfs_inode, maybe_i_size);
+                spin_unlock(&vnode->writeback_lock);
+        }
+
+        set_page_dirty(page);
+
+        if (PageDirty(page))
+                _debug("dirtied");
+
+        return 0;
+}
+
+/*
+ * kill all the pages in the given range
+ */
+static void afs_kill_pages(struct afs_vnode *vnode, bool error,
+                           pgoff_t first, pgoff_t last)
+{
+        struct pagevec pv;
+        unsigned count, loop;
+
+        _enter("{%x:%u},%lx-%lx",
+               vnode->fid.vid, vnode->fid.vnode, first, last);
+
+        pagevec_init(&pv, 0);
+
+        do {
+                _debug("kill %lx-%lx", first, last);
+
+                count = last - first + 1;
+                if (count > PAGEVEC_SIZE)
+                        count = PAGEVEC_SIZE;
+                pv.nr = find_get_pages_contig(vnode->vfs_inode.i_mapping,
+                                              first, count, pv.pages);
+                ASSERTCMP(pv.nr, ==, count);
+
+                for (loop = 0; loop < count; loop++) {
+                        ClearPageUptodate(pv.pages[loop]);
+                        if (error)
+                                SetPageError(pv.pages[loop]);
+                        end_page_writeback(pv.pages[loop]);
+                }
+
+                __pagevec_release(&pv);
+        } while (first < last);
+
+        _leave("");
+}
+
+/*
+ * synchronously write back the locked page and any subsequent non-locked dirty
+ * pages also covered by the same writeback record
+ */
+static int afs_write_back_from_locked_page(struct afs_writeback *wb,
+                                           struct page *primary_page)
+{
+        struct page *pages[8], *page;
+        unsigned long count;
+        unsigned n, offset, to;
+        pgoff_t start, first, last;
+        int loop, ret;
+
+        _enter(",%lx", primary_page->index);
+
+        count = 1;
+        if (!clear_page_dirty_for_io(primary_page))
+                BUG();
+        if (test_set_page_writeback(primary_page))
+                BUG();
+
+        /* find all consecutive lockable dirty pages, stopping when we find a
+         * page that is not immediately lockable, is not dirty or is missing,
+         * or we reach the end of the range */
+        start = primary_page->index;
+        if (start >= wb->last)
+                goto no_more;
+        start++;
+        do {
+                _debug("more %lx [%lx]", start, count);
+                n = wb->last - start + 1;
+                if (n > ARRAY_SIZE(pages))
+                        n = ARRAY_SIZE(pages);
+                n = find_get_pages_contig(wb->vnode->vfs_inode.i_mapping,
+                                          start, n, pages);
+                _debug("fgpc %u", n);
+                if (n == 0)
+                        goto no_more;
+                if (pages[0]->index != start) {
+                        for (n--; n >= 0; n--)
+                                put_page(pages[n]);
+                        goto no_more;
+                }
+
+                for (loop = 0; loop < n; loop++) {
+                        page = pages[loop];
+                        if (page->index > wb->last)
+                                break;
+                        if (TestSetPageLocked(page))
+                                break;
+                        if (!PageDirty(page) ||
+                            page_private(page) != (unsigned long) wb) {
+                                unlock_page(page);
+                                break;
+                        }
+                        if (!clear_page_dirty_for_io(page))
+                                BUG();
+                        if (test_set_page_writeback(page))
+                                BUG();
+                        unlock_page(page);
+                        put_page(page);
+                }
+                count += loop;
+                if (loop < n) {
+                        for (; loop < n; loop++)
+                                put_page(pages[loop]);
+                        goto no_more;
+                }
+
+                start += loop;
+        } while (start <= wb->last && count < 65536);
+
+no_more:
+        /* we now have a contiguous set of dirty pages, each with writeback set
+         * and the dirty mark cleared; the first page is locked and must remain
+         * so, all the rest are unlocked */
+        first = primary_page->index;
+        last = first + count - 1;
+
+        offset = (first == wb->first) ? wb->offset_first : 0;
+        to = (last == wb->last) ? wb->to_last : PAGE_SIZE;
+
+        _debug("write back %lx[%u..] to %lx[..%u]", first, offset, last, to);
+
+        ret = afs_vnode_store_data(wb, first, last, offset, to);
+        if (ret < 0) {
+                switch (ret) {
+                case -EDQUOT:
+                case -ENOSPC:
+                        set_bit(AS_ENOSPC,
+                                &wb->vnode->vfs_inode.i_mapping->flags);
+                        break;
+                case -EROFS:
+                case -EIO:
+                case -EREMOTEIO:
+                case -EFBIG:
+                case -ENOENT:
+                case -ENOMEDIUM:
+                case -ENXIO:
+                        afs_kill_pages(wb->vnode, true, first, last);
+                        set_bit(AS_EIO, &wb->vnode->vfs_inode.i_mapping->flags);
+                        break;
+                case -EACCES:
+                case -EPERM:
+                case -ENOKEY:
+                case -EKEYEXPIRED:
+                case -EKEYREJECTED:
+                case -EKEYREVOKED:
+                        afs_kill_pages(wb->vnode, false, first, last);
+                        break;
+                default:
+                        break;
+                }
+        } else {
+                ret = count;
+        }
+
+        _leave(" = %d", ret);
+        return ret;
+}
+
+/*
+ * write a page back to the server
+ * - the caller locked the page for us
+ */
+int afs_writepage(struct page *page, struct writeback_control *wbc)
+{
+        struct backing_dev_info *bdi = page->mapping->backing_dev_info;
+        struct afs_writeback *wb;
+        int ret;
+
+        _enter("{%lx},", page->index);
+
+        if (wbc->sync_mode != WB_SYNC_NONE)
+                wait_on_page_writeback(page);
+
+        if (PageWriteback(page) || !PageDirty(page)) {
+                unlock_page(page);
+                return 0;
+        }
+
+        wb = (struct afs_writeback *) page_private(page);
+        ASSERT(wb != NULL);
+
+        ret = afs_write_back_from_locked_page(wb, page);
+        unlock_page(page);
+        if (ret < 0) {
+                _leave(" = %d", ret);
+                return 0;
+        }
+
+        wbc->nr_to_write -= ret;
+        if (wbc->nonblocking && bdi_write_congested(bdi))
+                wbc->encountered_congestion = 1;
+
+        _leave(" = 0");
+        return 0;
+}
+
+/*
+ * write a region of pages back to the server
+ */
+int afs_writepages_region(struct address_space *mapping,
+                          struct writeback_control *wbc,
+                          pgoff_t index, pgoff_t end, pgoff_t *_next)
+{
+        struct backing_dev_info *bdi = mapping->backing_dev_info;
+        struct afs_writeback *wb;
+        struct page *page;
+        int ret, n;
+
+        _enter(",,%lx,%lx,", index, end);
+
+        do {
+                n = find_get_pages_tag(mapping, &index, PAGECACHE_TAG_DIRTY,
+                                       1, &page);
+                if (!n)
+                        break;
+
+                _debug("wback %lx", page->index);
+
+                if (page->index > end) {
+                        *_next = index;
+                        page_cache_release(page);
+                        _leave(" = 0 [%lx]", *_next);
+                        return 0;
+                }
+
+                /* at this point we hold neither mapping->tree_lock nor lock on
+                 * the page itself: the page may be truncated or invalidated
+                 * (changing page->mapping to NULL), or even swizzled back from
+                 * swapper_space to tmpfs file mapping
+                 */
+                lock_page(page);
+
+                if (page->mapping != mapping) {
+                        unlock_page(page);
+                        page_cache_release(page);
+                        continue;
+                }
+
+                if (wbc->sync_mode != WB_SYNC_NONE)
+                        wait_on_page_writeback(page);
+
+                if (PageWriteback(page) || !PageDirty(page)) {
+                        unlock_page(page);
+                        continue;
+                }
+
+                wb = (struct afs_writeback *) page_private(page);
+                ASSERT(wb != NULL);
+
+                spin_lock(&wb->vnode->writeback_lock);
+                wb->state = AFS_WBACK_WRITING;
+                spin_unlock(&wb->vnode->writeback_lock);
+
+                ret = afs_write_back_from_locked_page(wb, page);
+                unlock_page(page);
+                page_cache_release(page);
+                if (ret < 0) {
+                        _leave(" = %d", ret);
+                        return ret;
+                }
+
+                wbc->nr_to_write -= ret;
+
+                if (wbc->nonblocking && bdi_write_congested(bdi)) {
+                        wbc->encountered_congestion = 1;
+                        break;
+                }
+
+                cond_resched();
+        } while (index < end && wbc->nr_to_write > 0);
+
+        *_next = index;
+        _leave(" = 0 [%lx]", *_next);
+        return 0;
+}
+
+/*
+ * write some of the pending data back to the server
+ */
+int afs_writepages(struct address_space *mapping,
+                   struct writeback_control *wbc)
+{
+        struct backing_dev_info *bdi = mapping->backing_dev_info;
+        pgoff_t start, end, next;
+        int ret;
+
+        _enter("");
+
+        if (wbc->nonblocking && bdi_write_congested(bdi)) {
+                wbc->encountered_congestion = 1;
+                _leave(" = 0 [congest]");
+                return 0;
+        }
+
+        if (wbc->range_cyclic) {
+                start = mapping->writeback_index;
+                end = -1;
+                ret = afs_writepages_region(mapping, wbc, start, end, &next);
+                if (start > 0 && wbc->nr_to_write > 0 && ret == 0 &&
+                    !(wbc->nonblocking && wbc->encountered_congestion))
+                        ret = afs_writepages_region(mapping, wbc, 0, start,
+                                                    &next);
+                mapping->writeback_index = next;
+        } else if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) {
+                end = (pgoff_t)(LLONG_MAX >> PAGE_CACHE_SHIFT);
+                ret = afs_writepages_region(mapping, wbc, 0, end, &next);
+                if (wbc->nr_to_write > 0)
+                        mapping->writeback_index = next;
+        } else {
+                start = wbc->range_start >> PAGE_CACHE_SHIFT;
+                end = wbc->range_end >> PAGE_CACHE_SHIFT;
+                ret = afs_writepages_region(mapping, wbc, start, end, &next);
+        }
+
+        _leave(" = %d", ret);
+        return ret;
+}
+
+/*
+ * write an inode back
+ */
+int afs_write_inode(struct inode *inode, int sync)
+{
+        struct afs_vnode *vnode = AFS_FS_I(inode);
+        int ret;
+
+        _enter("{%x:%u},", vnode->fid.vid, vnode->fid.vnode);
+
+        ret = 0;
+        if (sync) {
+                ret = filemap_fdatawait(inode->i_mapping);
+                if (ret < 0)
+                        __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
+        }
+
+        _leave(" = %d", ret);
+        return ret;
+}
+
+/*
+ * completion of write to server
+ */
+void afs_pages_written_back(struct afs_vnode *vnode, struct afs_call *call)
+{
+        struct afs_writeback *wb = call->wb;
+        struct pagevec pv;
+        unsigned count, loop;
+        pgoff_t first = call->first, last = call->last;
+        bool free_wb;
+
+        _enter("{%x:%u},{%lx-%lx}",
+               vnode->fid.vid, vnode->fid.vnode, first, last);
+
+        ASSERT(wb != NULL);
+
+        pagevec_init(&pv, 0);
+
+        do {
+                _debug("attach %lx-%lx", first, last);
+
+                count = last - first + 1;
+                if (count > PAGEVEC_SIZE)
+                        count = PAGEVEC_SIZE;
+                pv.nr = find_get_pages_contig(call->mapping, first, count,
+                                              pv.pages);
+                ASSERTCMP(pv.nr, ==, count);
+
+                spin_lock(&vnode->writeback_lock);
+                for (loop = 0; loop < count; loop++) {
+                        struct page *page = pv.pages[loop];
+                        end_page_writeback(page);
+                        if (page_private(page) == (unsigned long) wb) {
+                                set_page_private(page, 0);
+                                ClearPagePrivate(page);
+                                wb->usage--;
+                        }
+                }
+                free_wb = false;
+                if (wb->usage == 0) {
+                        afs_unlink_writeback(wb);
+                        free_wb = true;
+                }
+                spin_unlock(&vnode->writeback_lock);
+                first += count;
+                if (free_wb) {
+                        afs_free_writeback(wb);
+                        wb = NULL;
+                }
+
+                __pagevec_release(&pv);
+        } while (first < last);
+
+        _leave("");
+}
+
+/*
+ * write to an AFS file
+ */
+ssize_t afs_file_write(struct kiocb *iocb, const struct iovec *iov,
+                       unsigned long nr_segs, loff_t pos)
+{
+        struct dentry *dentry = iocb->ki_filp->f_path.dentry;
+        struct afs_vnode *vnode = AFS_FS_I(dentry->d_inode);
+        ssize_t result;
+        size_t count = iov_length(iov, nr_segs);
+        int ret;
+
+        _enter("{%x.%u},{%zu},%lu,",
+               vnode->fid.vid, vnode->fid.vnode, count, nr_segs);
+
+        if (IS_SWAPFILE(&vnode->vfs_inode)) {
+                printk(KERN_INFO
+                       "AFS: Attempt to write to active swap file!\n");
+                return -EBUSY;
+        }
+
+        if (!count)
+                return 0;
+
+        result = generic_file_aio_write(iocb, iov, nr_segs, pos);
+        if (IS_ERR_VALUE(result)) {
+                _leave(" = %zd", result);
+                return result;
+        }
+
+        /* return error values for O_SYNC and IS_SYNC() */
+        if (IS_SYNC(&vnode->vfs_inode) || iocb->ki_filp->f_flags & O_SYNC) {
+                ret = afs_fsync(iocb->ki_filp, dentry, 1);
+                if (ret < 0)
+                        result = ret;
+        }
+
+        _leave(" = %zd", result);
+        return result;
+}
+
+/*
+ * flush the vnode to the fileserver
+ */
+int afs_writeback_all(struct afs_vnode *vnode)
+{
+        struct address_space *mapping = vnode->vfs_inode.i_mapping;
+        struct writeback_control wbc = {
+                .bdi            = mapping->backing_dev_info,
+                .sync_mode      = WB_SYNC_ALL,
+                .nr_to_write    = LONG_MAX,
+                .for_writepages = 1,
+                .range_cyclic   = 1,
+        };
+        int ret;
+
+        _enter("");
+
+        ret = mapping->a_ops->writepages(mapping, &wbc);
+        __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
+
+        _leave(" = %d", ret);
+        return ret;
+}
+
+/*
+ * flush any dirty pages for this process, and check for write errors.
+ * - the return status from this call provides a reliable indication of
+ *   whether any write errors occurred for this process.
+ */
+int afs_fsync(struct file *file, struct dentry *dentry, int datasync)
+{
+        struct afs_writeback *wb, *xwb;
+        struct afs_vnode *vnode = AFS_FS_I(dentry->d_inode);
+        int ret;
+
+        _enter("{%x:%u},{n=%s},%d",
+               vnode->fid.vid, vnode->fid.vnode, dentry->d_name.name,
+               datasync);
+
+        /* use a writeback record as a marker in the queue - when this reaches
+         * the front of the queue, all the outstanding writes are either
+         * completed or rejected */
+        wb = kzalloc(sizeof(*wb), GFP_KERNEL);
+        if (!wb)
+                return -ENOMEM;
+        wb->vnode = vnode;
+        wb->first = 0;
+        wb->last = -1;
+        wb->offset_first = 0;
+        wb->to_last = PAGE_SIZE;
+        wb->usage = 1;
+        wb->state = AFS_WBACK_SYNCING;
+        init_waitqueue_head(&wb->waitq);
+
+        spin_lock(&vnode->writeback_lock);
+        list_for_each_entry(xwb, &vnode->writebacks, link) {
+                if (xwb->state == AFS_WBACK_PENDING)
+                        xwb->state = AFS_WBACK_CONFLICTING;
+        }
+        list_add_tail(&wb->link, &vnode->writebacks);
+        spin_unlock(&vnode->writeback_lock);
+
+        /* push all the outstanding writebacks to the server */
+        ret = afs_writeback_all(vnode);
+        if (ret < 0) {
+                afs_put_writeback(wb);
+                _leave(" = %d [wb]", ret);
+                return ret;
+        }
+
+        /* wait for the preceding writes to actually complete */
+        ret = wait_event_interruptible(wb->waitq,
+                                       wb->state == AFS_WBACK_COMPLETE ||
+                                       vnode->writebacks.next == &wb->link);
+        afs_put_writeback(wb);
+        _leave(" = %d", ret);
+        return ret;
+}