2021-04-08 14:11:36

by David Howells

[permalink] [raw]
Subject: [PATCH v6 25/30] 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 <[email protected]>
cc: [email protected]
cc: [email protected]
cc: [email protected]
Link: https://lore.kernel.org/r/[email protected]g.uk/ # rfc
Link: https://lore.kernel.org/r/[email protected]rg.uk/
Link: https://lore.kernel.org/r/[email protected]org.uk/ # rfc
Link: https://lore.kernel.org/r/[email protected]rg.uk/ # rfc
Link: https://lore.kernel.org/r/[email protected]org.uk/ # v2
Link: https://lore.kernel.org/r/[email protected]rg.uk/ # v3
Link: https://lore.kernel.org/r/[email protected]g.uk/ # v4
Link: https://lore.kernel.org/r/[email protected]org.uk/ # v5
---

fs/afs/file.c | 9 +++++++++
fs/afs/write.c | 10 ++++++++++
2 files changed, 19 insertions(+)

diff --git a/fs/afs/file.c b/fs/afs/file.c
index 4a34ffaf6de4..f1e30b89e41c 100644
--- 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 6e41b982c71b..1b8cabf5ac92 100644
--- 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;
}