From: Trond Myklebust <[email protected]>
If a readdir call returns more data than we can fit into one page
cache page, then allocate a new one for that data rather than
discarding the data.
Signed-off-by: Trond Myklebust <[email protected]>
---
fs/nfs/dir.c | 46 ++++++++++++++++++++++++++++++++++++++++++----
1 file changed, 42 insertions(+), 4 deletions(-)
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index b4861a33ad60..788c2a2eeaa3 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -321,6 +321,26 @@ static void nfs_readdir_page_set_eof(struct page *page)
kunmap_atomic(array);
}
+static void nfs_readdir_page_unlock_and_put(struct page *page)
+{
+ unlock_page(page);
+ put_page(page);
+}
+
+static struct page *nfs_readdir_page_get_next(struct address_space *mapping,
+ pgoff_t index, u64 cookie)
+{
+ struct page *page;
+
+ page = nfs_readdir_page_get_locked(mapping, index, cookie);
+ if (page) {
+ if (nfs_readdir_page_last_cookie(page) == cookie)
+ return page;
+ nfs_readdir_page_unlock_and_put(page);
+ }
+ return NULL;
+}
+
static inline
int is_32bit_api(void)
{
@@ -638,13 +658,15 @@ void nfs_prime_dcache(struct dentry *parent, struct nfs_entry *entry,
}
/* Perform conversion from xdr to cache array */
-static
-int nfs_readdir_page_filler(nfs_readdir_descriptor_t *desc, struct nfs_entry *entry,
- struct page **xdr_pages, struct page *page, unsigned int buflen)
+static int nfs_readdir_page_filler(struct nfs_readdir_descriptor *desc,
+ struct nfs_entry *entry,
+ struct page **xdr_pages,
+ struct page *fillme, unsigned int buflen)
{
+ struct address_space *mapping = desc->file->f_mapping;
struct xdr_stream stream;
struct xdr_buf buf;
- struct page *scratch;
+ struct page *scratch, *new, *page = fillme;
int status;
scratch = alloc_page(GFP_KERNEL);
@@ -667,6 +689,19 @@ int nfs_readdir_page_filler(nfs_readdir_descriptor_t *desc, struct nfs_entry *en
desc->dir_verifier);
status = nfs_readdir_add_to_array(entry, page);
+ if (status != -ENOSPC)
+ continue;
+
+ if (page->mapping != mapping)
+ break;
+ new = nfs_readdir_page_get_next(mapping, page->index + 1,
+ entry->prev_cookie);
+ if (!new)
+ break;
+ if (page != fillme)
+ nfs_readdir_page_unlock_and_put(page);
+ page = new;
+ status = nfs_readdir_add_to_array(entry, page);
} while (!status && !entry->eof);
switch (status) {
@@ -682,6 +717,9 @@ int nfs_readdir_page_filler(nfs_readdir_descriptor_t *desc, struct nfs_entry *en
break;
}
+ if (page != fillme)
+ nfs_readdir_page_unlock_and_put(page);
+
put_page(scratch);
return status;
}
--
2.28.0
On 3 Nov 2020, at 10:33, [email protected] wrote:
> From: Trond Myklebust <[email protected]>
>
> If a readdir call returns more data than we can fit into one page
> cache page, then allocate a new one for that data rather than
> discarding the data.
>
> Signed-off-by: Trond Myklebust <[email protected]>
> ---
> fs/nfs/dir.c | 46 ++++++++++++++++++++++++++++++++++++++++++----
> 1 file changed, 42 insertions(+), 4 deletions(-)
>
> diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
> index b4861a33ad60..788c2a2eeaa3 100644
> --- a/fs/nfs/dir.c
> +++ b/fs/nfs/dir.c
> @@ -321,6 +321,26 @@ static void nfs_readdir_page_set_eof(struct page
> *page)
> kunmap_atomic(array);
> }
>
> +static void nfs_readdir_page_unlock_and_put(struct page *page)
> +{
> + unlock_page(page);
> + put_page(page);
> +}
> +
> +static struct page *nfs_readdir_page_get_next(struct address_space
> *mapping,
> + pgoff_t index, u64 cookie)
> +{
> + struct page *page;
> +
> + page = nfs_readdir_page_get_locked(mapping, index, cookie);
> + if (page) {
> + if (nfs_readdir_page_last_cookie(page) == cookie)
> + return page;
> + nfs_readdir_page_unlock_and_put(page);
> + }
> + return NULL;
> +}
> +
> static inline
> int is_32bit_api(void)
> {
> @@ -638,13 +658,15 @@ void nfs_prime_dcache(struct dentry *parent,
> struct nfs_entry *entry,
> }
>
> /* Perform conversion from xdr to cache array */
> -static
> -int nfs_readdir_page_filler(nfs_readdir_descriptor_t *desc, struct
> nfs_entry *entry,
> - struct page **xdr_pages, struct page *page, unsigned int buflen)
> +static int nfs_readdir_page_filler(struct nfs_readdir_descriptor
> *desc,
> + struct nfs_entry *entry,
> + struct page **xdr_pages,
> + struct page *fillme, unsigned int buflen)
> {
> + struct address_space *mapping = desc->file->f_mapping;
> struct xdr_stream stream;
> struct xdr_buf buf;
> - struct page *scratch;
> + struct page *scratch, *new, *page = fillme;
> int status;
>
> scratch = alloc_page(GFP_KERNEL);
> @@ -667,6 +689,19 @@ int
> nfs_readdir_page_filler(nfs_readdir_descriptor_t *desc, struct
> nfs_entry *en
> desc->dir_verifier);
>
> status = nfs_readdir_add_to_array(entry, page);
> + if (status != -ENOSPC)
> + continue;
> +
> + if (page->mapping != mapping)
> + break;
^^ How can this happen?
Ben
On Tue, 2020-11-03 at 10:55 -0500, Benjamin Coddington wrote:
> On 3 Nov 2020, at 10:33, [email protected] wrote:
>
> > From: Trond Myklebust <[email protected]>
> >
> > If a readdir call returns more data than we can fit into one page
> > cache page, then allocate a new one for that data rather than
> > discarding the data.
> >
> > Signed-off-by: Trond Myklebust <[email protected]>
> > ---
> > fs/nfs/dir.c | 46 ++++++++++++++++++++++++++++++++++++++++++----
> > 1 file changed, 42 insertions(+), 4 deletions(-)
> >
> > diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
> > index b4861a33ad60..788c2a2eeaa3 100644
> > --- a/fs/nfs/dir.c
> > +++ b/fs/nfs/dir.c
> > @@ -321,6 +321,26 @@ static void nfs_readdir_page_set_eof(struct
> > page
> > *page)
> > kunmap_atomic(array);
> > }
> >
> > +static void nfs_readdir_page_unlock_and_put(struct page *page)
> > +{
> > + unlock_page(page);
> > + put_page(page);
> > +}
> > +
> > +static struct page *nfs_readdir_page_get_next(struct address_space
> > *mapping,
> > + pgoff_t index, u64
> > cookie)
> > +{
> > + struct page *page;
> > +
> > + page = nfs_readdir_page_get_locked(mapping, index, cookie);
> > + if (page) {
> > + if (nfs_readdir_page_last_cookie(page) == cookie)
> > + return page;
> > + nfs_readdir_page_unlock_and_put(page);
> > + }
> > + return NULL;
> > +}
> > +
> > static inline
> > int is_32bit_api(void)
> > {
> > @@ -638,13 +658,15 @@ void nfs_prime_dcache(struct dentry *parent,
> > struct nfs_entry *entry,
> > }
> >
> > /* Perform conversion from xdr to cache array */
> > -static
> > -int nfs_readdir_page_filler(nfs_readdir_descriptor_t *desc, struct
> > nfs_entry *entry,
> > - struct page **xdr_pages, struct
> > page *page, unsigned int buflen)
> > +static int nfs_readdir_page_filler(struct nfs_readdir_descriptor
> > *desc,
> > + struct nfs_entry *entry,
> > + struct page **xdr_pages,
> > + struct page *fillme, unsigned
> > int buflen)
> > {
> > + struct address_space *mapping = desc->file->f_mapping;
> > struct xdr_stream stream;
> > struct xdr_buf buf;
> > - struct page *scratch;
> > + struct page *scratch, *new, *page = fillme;
> > int status;
> >
> > scratch = alloc_page(GFP_KERNEL);
> > @@ -667,6 +689,19 @@ int
> > nfs_readdir_page_filler(nfs_readdir_descriptor_t *desc, struct
> > nfs_entry *en
> > desc->dir_verifier);
> >
> > status = nfs_readdir_add_to_array(entry, page);
> > + if (status != -ENOSPC)
> > + continue;
> > +
> > + if (page->mapping != mapping)
> > + break;
>
> ^^ How can this happen?
>
We call the same routines from uncached_readdir(), so the above is
really there in order to exit when we see those anonymous pages.
--
Trond Myklebust
Linux NFS client maintainer, Hammerspace
[email protected]