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-rw-r--r--Documentation/filesystems/Locking8
-rw-r--r--fs/nfs/file.c16
-rw-r--r--include/linux/fs.h1
-rw-r--r--mm/truncate.c12
4 files changed, 28 insertions, 9 deletions
diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index 790ef6fbe495..28bfea75bcf2 100644
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -171,6 +171,7 @@ prototypes:
int (*releasepage) (struct page *, int);
int (*direct_IO)(int, struct kiocb *, const struct iovec *iov,
loff_t offset, unsigned long nr_segs);
+ int (*launder_page) (struct page *);
locking rules:
All except set_page_dirty may block
@@ -188,6 +189,7 @@ bmap: yes
invalidatepage: no yes
releasepage: no yes
direct_IO: no
+launder_page: no yes
->prepare_write(), ->commit_write(), ->sync_page() and ->readpage()
may be called from the request handler (/dev/loop).
@@ -281,6 +283,12 @@ buffers from the page in preparation for freeing it. It returns zero to
indicate that the buffers are (or may be) freeable. If ->releasepage is zero,
the kernel assumes that the fs has no private interest in the buffers.
+ ->launder_page() may be called prior to releasing a page if
+it is still found to be dirty. It returns zero if the page was successfully
+cleaned, or an error value if not. Note that in order to prevent the page
+getting mapped back in and redirtied, it needs to be kept locked
+across the entire operation.
+
Note: currently almost all instances of address_space methods are
using BKL for internal serialization and that's one of the worst sources
of contention. Normally they are calling library functions (in fs/buffer.c)
diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 0dd6be346aa7..fab20d06d936 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -315,14 +315,13 @@ static void nfs_invalidate_page(struct page *page, unsigned long offset)
static int nfs_release_page(struct page *page, gfp_t gfp)
{
- /*
- * Avoid deadlock on nfs_wait_on_request().
- */
- if (!(gfp & __GFP_FS))
- return 0;
- /* Hack... Force nfs_wb_page() to write out the page */
- SetPageDirty(page);
- return !nfs_wb_page(page->mapping->host, page);
+ /* If PagePrivate() is set, then the page is not freeable */
+ return 0;
+}
+
+static int nfs_launder_page(struct page *page)
+{
+ return nfs_wb_page(page->mapping->host, page);
}
const struct address_space_operations nfs_file_aops = {
@@ -338,6 +337,7 @@ const struct address_space_operations nfs_file_aops = {
#ifdef CONFIG_NFS_DIRECTIO
.direct_IO = nfs_direct_IO,
#endif
+ .launder_page = nfs_launder_page,
};
static ssize_t nfs_file_write(struct kiocb *iocb, const struct iovec *iov,
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 186da813541e..14a337cc3464 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -426,6 +426,7 @@ struct address_space_operations {
/* migrate the contents of a page to the specified target */
int (*migratepage) (struct address_space *,
struct page *, struct page *);
+ int (*launder_page) (struct page *);
};
struct backing_dev_info;
diff --git a/mm/truncate.c b/mm/truncate.c
index ecdfdcc50522..6c79ca4a1ca7 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -341,6 +341,15 @@ failed:
return 0;
}
+static int do_launder_page(struct address_space *mapping, struct page *page)
+{
+ if (!PageDirty(page))
+ return 0;
+ if (page->mapping != mapping || mapping->a_ops->launder_page == NULL)
+ return 0;
+ return mapping->a_ops->launder_page(page);
+}
+
/**
* invalidate_inode_pages2_range - remove range of pages from an address_space
* @mapping: the address_space
@@ -405,7 +414,8 @@ int invalidate_inode_pages2_range(struct address_space *mapping,
PAGE_CACHE_SIZE, 0);
}
}
- if (!invalidate_complete_page2(mapping, page))
+ ret = do_launder_page(mapping, page);
+ if (ret == 0 && !invalidate_complete_page2(mapping, page))
ret = -EIO;
unlock_page(page);
}