afs: Wait on PG_fscache before modifying/releasing a page

PG_fscache is going to be used to indicate that a page is being written to
the cache, and that the page should not be modified or released until it's
finished.

Make afs_invalidatepage() and afs_releasepage() wait for it.

Signed-off-by: David Howells <dhowells@redhat.com>
Tested-By: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
cc: linux-cachefs@redhat.com
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/158861253957.340223.7465334678444521655.stgit@warthog.procyon.org.uk/
Link: https://lore.kernel.org/r/159465832417.1377938.3571599385208729791.stgit@warthog.procyon.org.uk/
Link: https://lore.kernel.org/r/160588536286.3465195.13231895135369807920.stgit@warthog.procyon.org.uk/
Link: https://lore.kernel.org/r/161118153708.1232039.3535103645871176749.stgit@warthog.procyon.org.uk/
Link: https://lore.kernel.org/r/161161049369.2537118.11591934943429117060.stgit@warthog.procyon.org.uk/
Link: https://lore.kernel.org/r/161340412903.1303470.6424701655031380012.stgit@warthog.procyon.org.uk/
Link: https://lore.kernel.org/r/161539556890.286939.5873470593519458598.stgit@warthog.procyon.org.uk/
Link: https://lore.kernel.org/r/161653812726.2770958.18167145829938766503.stgit@warthog.procyon.org.uk/
Link: https://lore.kernel.org/r/161789096241.6155.5907241930823579235.stgit@warthog.procyon.org.uk/

diff --git a/fs/afs/file.c b/fs/afs/file.c
index 4a34ffaf6de4e7f192bc006ba4bb8b34f1963924..f1e30b89e41cf17b40067c8ad439c28d6ef350ec 100644 (file)
--- a/fs/afs/file.c
+++ b/fs/afs/file.c
@@ -593,6 +593,7 @@ static void afs_invalidatepage(struct page *page, unsigned int offset,
        if (PagePrivate(page))
                afs_invalidate_dirty(page, offset, length);
 
+       wait_on_page_fscache(page);
        _leave("");
 }
 
@@ -610,6 +611,14 @@ static int afs_releasepage(struct page *page, gfp_t gfp_flags)
 
        /* deny if page is being written to the cache and the caller hasn't
         * elected to wait */
+#ifdef CONFIG_AFS_FSCACHE
+       if (PageFsCache(page)) {
+               if (!(gfp_flags & __GFP_DIRECT_RECLAIM) || !(gfp_flags & __GFP_FS))
+                       return false;
+               wait_on_page_fscache(page);
+       }
+#endif
+
        if (PagePrivate(page)) {
                detach_page_private(page);
                trace_afs_page_dirty(vnode, tracepoint_string("rel"), page);

diff --git a/fs/afs/write.c b/fs/afs/write.c
index 6e41b982c71b9ff3146dc67ae1a35a2ecd8db3f1..1b8cabf5ac92f32e135ae2d58800c18a4ce0b60b 100644 (file)
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -117,6 +117,10 @@ int afs_write_begin(struct file *file, struct address_space *mapping,
                SetPageUptodate(page);
        }
 
+#ifdef CONFIG_AFS_FSCACHE
+       wait_on_page_fscache(page);
+#endif
+
 try_again:
        /* See if this page is already partially written in a way that we can
         * merge the new write with.
@@ -857,6 +861,11 @@ vm_fault_t afs_page_mkwrite(struct vm_fault *vmf)
        /* Wait for the page to be written to the cache before we allow it to
         * be modified.  We then assume the entire page will need writing back.
         */
+#ifdef CONFIG_AFS_FSCACHE
+       if (PageFsCache(vmf->page) &&
+           wait_on_page_bit_killable(vmf->page, PG_fscache) < 0)
+               return VM_FAULT_RETRY;
+#endif
 
        if (wait_on_page_writeback_killable(vmf->page))
                return VM_FAULT_RETRY;
@@ -947,5 +956,6 @@ int afs_launder_page(struct page *page)
 
        detach_page_private(page);
        trace_afs_page_dirty(vnode, tracepoint_string("laundered"), page);
+       wait_on_page_fscache(page);
        return ret;
 }