| Message ID | 20231013160423.2218093-13-dhowells@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | netfs, afs, cifs: Delegate high-level I/O to netfslib | expand |
On Fri, Oct 13, 2023 at 05:03:41PM +0100, David Howells wrote: > +int netfs_xa_store_and_mark(struct xarray *xa, unsigned long index, > + struct folio *folio, bool put_mark, > + bool pagecache_mark, gfp_t gfp_mask); Linus has been unhappy recently with functions that take two bools. When you're reading the caller, you see: netfs_xa_store_and_mark(xa, index, true, false, GFP_FOO); and you don't know instantly what true and false mean. He prefers #define NETFS_FLAG_PUT (1 << 0) #define NETFS_FLAG_PAGECACHE (1 << 1) and then the caller looks like: netfs_xa_store_and_mark(xa, index, NETFS_FLAG_PUT, GFP_FOO); and you know exactly what it's doing.
On Fri, 2023-10-13 at 17:03 +0100, David Howells wrote: > Provide tools to create a buffer in an xarray, with a function to add > new folios with a mark. This will be used to create bounce buffer and can be > used more easily to create a list of folios the span of which would require > more than a page's worth of bio_vec structs. > > Signed-off-by: David Howells <dhowells@redhat.com> > cc: Jeff Layton <jlayton@kernel.org> > cc: linux-cachefs@redhat.com > cc: linux-fsdevel@vger.kernel.org > cc: linux-mm@kvack.org > --- > fs/netfs/internal.h | 16 +++++ > fs/netfs/misc.c | 140 ++++++++++++++++++++++++++++++++++++++++++ > include/linux/netfs.h | 4 ++ > 3 files changed, 160 insertions(+) > > diff --git a/fs/netfs/internal.h b/fs/netfs/internal.h > index 1f067aa96c50..00e01278316f 100644 > --- a/fs/netfs/internal.h > +++ b/fs/netfs/internal.h > @@ -52,6 +52,22 @@ static inline void netfs_proc_add_rreq(struct netfs_io_request *rreq) {} > static inline void netfs_proc_del_rreq(struct netfs_io_request *rreq) {} > #endif > > +/* > + * misc.c > + */ > +int netfs_xa_store_and_mark(struct xarray *xa, unsigned long index, > + struct folio *folio, bool put_mark, > + bool pagecache_mark, gfp_t gfp_mask); > +int netfs_add_folios_to_buffer(struct xarray *buffer, > + struct address_space *mapping, > + pgoff_t index, pgoff_t to, gfp_t gfp_mask); > +int netfs_set_up_buffer(struct xarray *buffer, > + struct address_space *mapping, > + struct readahead_control *ractl, > + struct folio *keep, > + pgoff_t have_index, unsigned int have_folios); > +void netfs_clear_buffer(struct xarray *buffer); > + > /* > * objects.c > */ > diff --git a/fs/netfs/misc.c b/fs/netfs/misc.c > index c3baf2b247d9..c70f856f3129 100644 > --- a/fs/netfs/misc.c > +++ b/fs/netfs/misc.c > @@ -8,6 +8,146 @@ > #include <linux/swap.h> > #include "internal.h" > > +/* > + * Attach a folio to the buffer and maybe set marks on it to say that we need > + * to put the folio later and twiddle the pagecache flags. > + */ > +int netfs_xa_store_and_mark(struct xarray *xa, unsigned long index, > + struct folio *folio, bool put_mark, > + bool pagecache_mark, gfp_t gfp_mask) > +{ > + XA_STATE_ORDER(xas, xa, index, folio_order(folio)); > + > +retry: > + xas_lock(&xas); > + for (;;) { > + xas_store(&xas, folio); > + if (!xas_error(&xas)) > + break; > + xas_unlock(&xas); > + if (!xas_nomem(&xas, gfp_mask)) > + return xas_error(&xas); > + goto retry; > + } > + > + if (put_mark) > + xas_set_mark(&xas, NETFS_BUF_PUT_MARK); > + if (pagecache_mark) > + xas_set_mark(&xas, NETFS_BUF_PAGECACHE_MARK); > + xas_unlock(&xas); > + return xas_error(&xas); > +} > + > +/* > + * Create the specified range of folios in the buffer attached to the read > + * request. The folios are marked with NETFS_BUF_PUT_MARK so that we know that > + * these need freeing later. > + */ Some kerneldoc comments on these new helpers would be nice. I assume that "index" and "to" are "start" and "end" for this, but it'd be nice to make that explicit. > +int netfs_add_folios_to_buffer(struct xarray *buffer, > + struct address_space *mapping, > + pgoff_t index, pgoff_t to, gfp_t gfp_mask) > +{ > + struct folio *folio; > + int ret; > + > + if (to + 1 == index) /* Page range is inclusive */ > + return 0; > + > + do { > + /* TODO: Figure out what order folio can be allocated here */ > + folio = filemap_alloc_folio(readahead_gfp_mask(mapping), 0); > + if (!folio) > + return -ENOMEM; > + folio->index = index; > + ret = netfs_xa_store_and_mark(buffer, index, folio, > + true, false, gfp_mask); > + if (ret < 0) { > + folio_put(folio); > + return ret; > + } > + > + index += folio_nr_pages(folio); > + } while (index <= to && index != 0); > + > + return 0; > +} > + > +/* > + * Set up a buffer into which to data will be read or decrypted/decompressed. > + * The folios to be read into are attached to this buffer and the gaps filled > + * in to form a continuous region. > + */ > +int netfs_set_up_buffer(struct xarray *buffer, > + struct address_space *mapping, > + struct readahead_control *ractl, > + struct folio *keep, > + pgoff_t have_index, unsigned int have_folios) > +{ > + struct folio *folio; > + gfp_t gfp_mask = readahead_gfp_mask(mapping); > + unsigned int want_folios = have_folios; > + pgoff_t want_index = have_index; > + int ret; > + > + ret = netfs_add_folios_to_buffer(buffer, mapping, want_index, > + have_index - 1, gfp_mask); > + if (ret < 0) > + return ret; > + have_folios += have_index - want_index; > + > + ret = netfs_add_folios_to_buffer(buffer, mapping, > + have_index + have_folios, > + want_index + want_folios - 1, > + gfp_mask); I don't get it. Why are you calling netfs_add_folios_to_buffer twice here? Why not just make one call? Either way, a comment here explaining that would also be nice. > + if (ret < 0) > + return ret; > + > + /* Transfer the folios proposed by the VM into the buffer and take refs > + * on them. The locks will be dropped in netfs_rreq_unlock(). > + */ > + if (ractl) { > + while ((folio = readahead_folio(ractl))) { > + folio_get(folio); > + if (folio == keep) > + folio_get(folio); > + ret = netfs_xa_store_and_mark(buffer, folio->index, folio, > + true, true, gfp_mask); > + if (ret < 0) { > + if (folio != keep) > + folio_unlock(folio); > + folio_put(folio); > + return ret; > + } > + } > + } else { > + folio_get(keep); > + ret = netfs_xa_store_and_mark(buffer, keep->index, keep, > + true, true, gfp_mask); > + if (ret < 0) { > + folio_put(keep); > + return ret; > + } > + } > + return 0; > +} > + > +/* > + * Clear an xarray buffer, putting a ref on the folios that have > + * NETFS_BUF_PUT_MARK set. > + */ > +void netfs_clear_buffer(struct xarray *buffer) > +{ > + struct folio *folio; > + XA_STATE(xas, buffer, 0); > + > + rcu_read_lock(); > + xas_for_each_marked(&xas, folio, ULONG_MAX, NETFS_BUF_PUT_MARK) { > + folio_put(folio); > + } > + rcu_read_unlock(); > + xa_destroy(buffer); > +} > + > /** > * netfs_invalidate_folio - Invalidate or partially invalidate a folio > * @folio: Folio proposed for release > diff --git a/include/linux/netfs.h b/include/linux/netfs.h > index 66479a61ad00..e8d702ac6968 100644 > --- a/include/linux/netfs.h > +++ b/include/linux/netfs.h > @@ -109,6 +109,10 @@ static inline int wait_on_page_fscache_killable(struct page *page) > return folio_wait_private_2_killable(page_folio(page)); > } > > +/* Marks used on xarray-based buffers */ > +#define NETFS_BUF_PUT_MARK XA_MARK_0 /* - Page needs putting */ > +#define NETFS_BUF_PAGECACHE_MARK XA_MARK_1 /* - Page needs wb/dirty flag wrangling */ > + > enum netfs_io_source { > NETFS_FILL_WITH_ZEROES, > NETFS_DOWNLOAD_FROM_SERVER, >
Jeff Layton <jlayton@kernel.org> wrote: > Some kerneldoc comments on these new helpers would be nice. I assume > that "index" and "to" are "start" and "end" for this, but it'd be nice > to make that explicit. These are internal to netfs not API functions, so they shouldn't appear in the API docs. That's why the declaration is in internal.h, not netfs.h. That said, I could describe them better. > > + ret = netfs_add_folios_to_buffer(buffer, mapping, want_index, > > + have_index - 1, gfp_mask); > > + if (ret < 0) > > + return ret; > > + have_folios += have_index - want_index; > > + > > + ret = netfs_add_folios_to_buffer(buffer, mapping, > > + have_index + have_folios, > > + want_index + want_folios - 1, > > + gfp_mask); > > I don't get it. Why are you calling netfs_add_folios_to_buffer twice > here? Why not just make one call? Either way, a comment here explaining > that would also be nice. The ranges aren't contiguous. They bracket the folios spliced from the mapping. That being said, I seem to have lost a bit of maths somewhere. Further, I'm not now using netfs_add_folios_to_buffer(), so I'll remove it. David
diff --git a/fs/netfs/internal.h b/fs/netfs/internal.h index 1f067aa96c50..00e01278316f 100644 --- a/fs/netfs/internal.h +++ b/fs/netfs/internal.h @@ -52,6 +52,22 @@ static inline void netfs_proc_add_rreq(struct netfs_io_request *rreq) {} static inline void netfs_proc_del_rreq(struct netfs_io_request *rreq) {} #endif +/* + * misc.c + */ +int netfs_xa_store_and_mark(struct xarray *xa, unsigned long index, + struct folio *folio, bool put_mark, + bool pagecache_mark, gfp_t gfp_mask); +int netfs_add_folios_to_buffer(struct xarray *buffer, + struct address_space *mapping, + pgoff_t index, pgoff_t to, gfp_t gfp_mask); +int netfs_set_up_buffer(struct xarray *buffer, + struct address_space *mapping, + struct readahead_control *ractl, + struct folio *keep, + pgoff_t have_index, unsigned int have_folios); +void netfs_clear_buffer(struct xarray *buffer); + /* * objects.c */ diff --git a/fs/netfs/misc.c b/fs/netfs/misc.c index c3baf2b247d9..c70f856f3129 100644 --- a/fs/netfs/misc.c +++ b/fs/netfs/misc.c @@ -8,6 +8,146 @@ #include <linux/swap.h> #include "internal.h" +/* + * Attach a folio to the buffer and maybe set marks on it to say that we need + * to put the folio later and twiddle the pagecache flags. + */ +int netfs_xa_store_and_mark(struct xarray *xa, unsigned long index, + struct folio *folio, bool put_mark, + bool pagecache_mark, gfp_t gfp_mask) +{ + XA_STATE_ORDER(xas, xa, index, folio_order(folio)); + +retry: + xas_lock(&xas); + for (;;) { + xas_store(&xas, folio); + if (!xas_error(&xas)) + break; + xas_unlock(&xas); + if (!xas_nomem(&xas, gfp_mask)) + return xas_error(&xas); + goto retry; + } + + if (put_mark) + xas_set_mark(&xas, NETFS_BUF_PUT_MARK); + if (pagecache_mark) + xas_set_mark(&xas, NETFS_BUF_PAGECACHE_MARK); + xas_unlock(&xas); + return xas_error(&xas); +} + +/* + * Create the specified range of folios in the buffer attached to the read + * request. The folios are marked with NETFS_BUF_PUT_MARK so that we know that + * these need freeing later. + */ +int netfs_add_folios_to_buffer(struct xarray *buffer, + struct address_space *mapping, + pgoff_t index, pgoff_t to, gfp_t gfp_mask) +{ + struct folio *folio; + int ret; + + if (to + 1 == index) /* Page range is inclusive */ + return 0; + + do { + /* TODO: Figure out what order folio can be allocated here */ + folio = filemap_alloc_folio(readahead_gfp_mask(mapping), 0); + if (!folio) + return -ENOMEM; + folio->index = index; + ret = netfs_xa_store_and_mark(buffer, index, folio, + true, false, gfp_mask); + if (ret < 0) { + folio_put(folio); + return ret; + } + + index += folio_nr_pages(folio); + } while (index <= to && index != 0); + + return 0; +} + +/* + * Set up a buffer into which to data will be read or decrypted/decompressed. + * The folios to be read into are attached to this buffer and the gaps filled + * in to form a continuous region. + */ +int netfs_set_up_buffer(struct xarray *buffer, + struct address_space *mapping, + struct readahead_control *ractl, + struct folio *keep, + pgoff_t have_index, unsigned int have_folios) +{ + struct folio *folio; + gfp_t gfp_mask = readahead_gfp_mask(mapping); + unsigned int want_folios = have_folios; + pgoff_t want_index = have_index; + int ret; + + ret = netfs_add_folios_to_buffer(buffer, mapping, want_index, + have_index - 1, gfp_mask); + if (ret < 0) + return ret; + have_folios += have_index - want_index; + + ret = netfs_add_folios_to_buffer(buffer, mapping, + have_index + have_folios, + want_index + want_folios - 1, + gfp_mask); + if (ret < 0) + return ret; + + /* Transfer the folios proposed by the VM into the buffer and take refs + * on them. The locks will be dropped in netfs_rreq_unlock(). + */ + if (ractl) { + while ((folio = readahead_folio(ractl))) { + folio_get(folio); + if (folio == keep) + folio_get(folio); + ret = netfs_xa_store_and_mark(buffer, folio->index, folio, + true, true, gfp_mask); + if (ret < 0) { + if (folio != keep) + folio_unlock(folio); + folio_put(folio); + return ret; + } + } + } else { + folio_get(keep); + ret = netfs_xa_store_and_mark(buffer, keep->index, keep, + true, true, gfp_mask); + if (ret < 0) { + folio_put(keep); + return ret; + } + } + return 0; +} + +/* + * Clear an xarray buffer, putting a ref on the folios that have + * NETFS_BUF_PUT_MARK set. + */ +void netfs_clear_buffer(struct xarray *buffer) +{ + struct folio *folio; + XA_STATE(xas, buffer, 0); + + rcu_read_lock(); + xas_for_each_marked(&xas, folio, ULONG_MAX, NETFS_BUF_PUT_MARK) { + folio_put(folio); + } + rcu_read_unlock(); + xa_destroy(buffer); +} + /** * netfs_invalidate_folio - Invalidate or partially invalidate a folio * @folio: Folio proposed for release diff --git a/include/linux/netfs.h b/include/linux/netfs.h index 66479a61ad00..e8d702ac6968 100644 --- a/include/linux/netfs.h +++ b/include/linux/netfs.h @@ -109,6 +109,10 @@ static inline int wait_on_page_fscache_killable(struct page *page) return folio_wait_private_2_killable(page_folio(page)); } +/* Marks used on xarray-based buffers */ +#define NETFS_BUF_PUT_MARK XA_MARK_0 /* - Page needs putting */ +#define NETFS_BUF_PAGECACHE_MARK XA_MARK_1 /* - Page needs wb/dirty flag wrangling */ + enum netfs_io_source { NETFS_FILL_WITH_ZEROES, NETFS_DOWNLOAD_FROM_SERVER,
Provide tools to create a buffer in an xarray, with a function to add new folios with a mark. This will be used to create bounce buffer and can be used more easily to create a list of folios the span of which would require more than a page's worth of bio_vec structs. Signed-off-by: David Howells <dhowells@redhat.com> cc: Jeff Layton <jlayton@kernel.org> cc: linux-cachefs@redhat.com cc: linux-fsdevel@vger.kernel.org cc: linux-mm@kvack.org --- fs/netfs/internal.h | 16 +++++ fs/netfs/misc.c | 140 ++++++++++++++++++++++++++++++++++++++++++ include/linux/netfs.h | 4 ++ 3 files changed, 160 insertions(+)