| Message ID | 163706992597.3179783.18360472879717076435.stgit@warthog.procyon.org.uk (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | netfs: Adjust docs after foliation | expand |
On Tue, 2021-11-16 at 13:38 +0000, David Howells wrote: > Adjust the netfslib docs in light of the foliation changes. > > Also un-kdoc-mark netfs_skip_folio_read() since it's internal and isn't > part of the API. > > Signed-off-by: David Howells <dhowells@redhat.com> > cc: Matthew Wilcox <willy@infradead.org> > cc: linux-cachefs@redhat.com > cc: linux-mm@kvack.org > --- > > Documentation/filesystems/netfs_library.rst | 95 ++++++++++++++++----------- > fs/netfs/read_helper.c | 4 + > 2 files changed, 58 insertions(+), 41 deletions(-) > > diff --git a/Documentation/filesystems/netfs_library.rst b/Documentation/filesystems/netfs_library.rst > index bb68d39f03b7..375baca7edcd 100644 > --- a/Documentation/filesystems/netfs_library.rst > +++ b/Documentation/filesystems/netfs_library.rst > @@ -1,7 +1,7 @@ > .. SPDX-License-Identifier: GPL-2.0 > > ================================= > -NETWORK FILESYSTEM HELPER LIBRARY > +Network Filesystem Helper Library > ================================= > > .. Contents: > @@ -37,22 +37,22 @@ into a common call framework. > > The following services are provided: > > - * Handles transparent huge pages (THPs). > + * Handle folios that span multiple pages. > > - * Insulates the netfs from VM interface changes. > + * Insulate the netfs from VM interface changes. > > - * Allows the netfs to arbitrarily split reads up into pieces, even ones that > - don't match page sizes or page alignments and that may cross pages. > + * Allow the netfs to arbitrarily split reads up into pieces, even ones that > + don't match folio sizes or folio alignments and that may cross folios. > > - * Allows the netfs to expand a readahead request in both directions to meet > - its needs. > + * Allow the netfs to expand a readahead request in both directions to meet its > + needs. > > - * Allows the netfs to partially fulfil a read, which will then be resubmitted. > + * Allow the netfs to partially fulfil a read, which will then be resubmitted. > > - * Handles local caching, allowing cached data and server-read data to be > + * Handle local caching, allowing cached data and server-read data to be > interleaved for a single request. > > - * Handles clearing of bufferage that aren't on the server. > + * Handle clearing of bufferage that aren't on the server. > > * Handle retrying of reads that failed, switching reads from the cache to the > server as necessary. > @@ -70,22 +70,22 @@ Read Helper Functions > > Three read helpers are provided:: > > - * void netfs_readahead(struct readahead_control *ractl, > - const struct netfs_read_request_ops *ops, > - void *netfs_priv);`` > - * int netfs_readpage(struct file *file, > - struct page *page, > - const struct netfs_read_request_ops *ops, > - void *netfs_priv); > - * int netfs_write_begin(struct file *file, > - struct address_space *mapping, > - loff_t pos, > - unsigned int len, > - unsigned int flags, > - struct page **_page, > - void **_fsdata, > - const struct netfs_read_request_ops *ops, > - void *netfs_priv); > + void netfs_readahead(struct readahead_control *ractl, > + const struct netfs_read_request_ops *ops, > + void *netfs_priv); > + int netfs_readpage(struct file *file, > + struct folio *folio, > + const struct netfs_read_request_ops *ops, > + void *netfs_priv); > + int netfs_write_begin(struct file *file, > + struct address_space *mapping, > + loff_t pos, > + unsigned int len, > + unsigned int flags, > + struct folio **_folio, > + void **_fsdata, > + const struct netfs_read_request_ops *ops, > + void *netfs_priv); > > Each corresponds to a VM operation, with the addition of a couple of parameters > for the use of the read helpers: > @@ -103,8 +103,8 @@ Both of these values will be stored into the read request structure. > For ->readahead() and ->readpage(), the network filesystem should just jump > into the corresponding read helper; whereas for ->write_begin(), it may be a > little more complicated as the network filesystem might want to flush > -conflicting writes or track dirty data and needs to put the acquired page if an > -error occurs after calling the helper. > +conflicting writes or track dirty data and needs to put the acquired folio if > +an error occurs after calling the helper. > > The helpers manage the read request, calling back into the network filesystem > through the suppplied table of operations. Waits will be performed as > @@ -253,7 +253,7 @@ through which it can issue requests and negotiate:: > void (*issue_op)(struct netfs_read_subrequest *subreq); > bool (*is_still_valid)(struct netfs_read_request *rreq); > int (*check_write_begin)(struct file *file, loff_t pos, unsigned len, > - struct page *page, void **_fsdata); > + struct folio *folio, void **_fsdata); > void (*done)(struct netfs_read_request *rreq); > void (*cleanup)(struct address_space *mapping, void *netfs_priv); > }; > @@ -313,13 +313,14 @@ The operations are as follows: > > There is no return value; the netfs_subreq_terminated() function should be > called to indicate whether or not the operation succeeded and how much data > - it transferred. The filesystem also should not deal with setting pages > + it transferred. The filesystem also should not deal with setting folios > uptodate, unlocking them or dropping their refs - the helpers need to deal > with this as they have to coordinate with copying to the local cache. > > - Note that the helpers have the pages locked, but not pinned. It is possible > - to use the ITER_XARRAY iov iterator to refer to the range of the inode that > - is being operated upon without the need to allocate large bvec tables. > + Note that the helpers have the folios locked, but not pinned. It is > + possible to use the ITER_XARRAY iov iterator to refer to the range of the > + inode that is being operated upon without the need to allocate large bvec > + tables. > > * ``is_still_valid()`` > > @@ -330,15 +331,15 @@ The operations are as follows: > * ``check_write_begin()`` > > [Optional] This is called from the netfs_write_begin() helper once it has > - allocated/grabbed the page to be modified to allow the filesystem to flush > + allocated/grabbed the folio to be modified to allow the filesystem to flush > conflicting state before allowing it to be modified. > > - It should return 0 if everything is now fine, -EAGAIN if the page should be > + It should return 0 if everything is now fine, -EAGAIN if the folio should be > regrabbed and any other error code to abort the operation. > > * ``done`` > > - [Optional] This is called after the pages in the request have all been > + [Optional] This is called after the folios in the request have all been > unlocked (and marked uptodate if applicable). > > * ``cleanup`` > @@ -390,7 +391,7 @@ The read helpers work by the following general procedure: > * If NETFS_SREQ_CLEAR_TAIL was set, a short read will be cleared to the > end of the slice instead of reissuing. > > - * Once the data is read, the pages that have been fully read/cleared: > + * Once the data is read, the folios that have been fully read/cleared: > > * Will be marked uptodate. > > @@ -398,11 +399,11 @@ The read helpers work by the following general procedure: > > * Unlocked > > - * Any pages that need writing to the cache will then have DIO writes issued. > + * Any folios that need writing to the cache will then have DIO writes issued. > > * Synchronous operations will wait for reading to be complete. > > - * Writes to the cache will proceed asynchronously and the pages will have the > + * Writes to the cache will proceed asynchronously and the folios will have the > PG_fscache mark removed when that completes. > > * The request structures will be cleaned up when everything has completed. > @@ -452,6 +453,9 @@ operation table looks like the following:: > netfs_io_terminated_t term_func, > void *term_func_priv); > > + int (*prepare_write)(struct netfs_cache_resources *cres, > + loff_t *_start, size_t *_len, loff_t i_size); > + > int (*write)(struct netfs_cache_resources *cres, > loff_t start_pos, > struct iov_iter *iter, > @@ -509,6 +513,14 @@ The methods defined in the table are: > indicating whether the termination is definitely happening in the caller's > context. > > + * ``prepare_write()`` > + > + [Required] Called to adjust a write to the cache and check that there is > + sufficient space in the cache. The start and length values indicate the > + size of the write that netfslib is proposing, and this can be adjusted by > + the cache to respect DIO boundaries. The file size is passed for > + information. > + > * ``write()`` > > [Required] Called to write to the cache. The start file offset is given > @@ -525,4 +537,9 @@ not the read request structure as they could be used in other situations where > there isn't a read request structure as well, such as writing dirty data to the > cache. > > + > +API Function Reference > +====================== > + > .. kernel-doc:: include/linux/netfs.h > +.. kernel-doc:: fs/netfs/read_helper.c > diff --git a/fs/netfs/read_helper.c b/fs/netfs/read_helper.c > index 9320a42dfaf9..7046f9bdd8dc 100644 > --- a/fs/netfs/read_helper.c > +++ b/fs/netfs/read_helper.c > @@ -1008,8 +1008,8 @@ int netfs_readpage(struct file *file, > } > EXPORT_SYMBOL(netfs_readpage); > > -/** > - * netfs_skip_folio_read - prep a folio for writing without reading first > +/* > + * Prepare a folio for writing without reading first > * @folio: The folio being prepared > * @pos: starting position for the write > * @len: length of write > > Not sure why you decided to change the last one not to be a kerneldoc comment, but OK. The rest of the changes look straightforward. Reviewed-by: Jeff Layton <jlayton@redhat.com>
Jeff Layton <jlayton@redhat.com> wrote: > > -/** > > - * netfs_skip_folio_read - prep a folio for writing without reading first > > +/* > ... > Not sure why you decided to change the last one not to be a kerneldoc > comment, but OK. The rest of the changes look straightforward. It's not part of the API. It's only internal. None of the other internal functions are listed in the API reference. David
diff --git a/Documentation/filesystems/netfs_library.rst b/Documentation/filesystems/netfs_library.rst index bb68d39f03b7..375baca7edcd 100644 --- a/Documentation/filesystems/netfs_library.rst +++ b/Documentation/filesystems/netfs_library.rst @@ -1,7 +1,7 @@ .. SPDX-License-Identifier: GPL-2.0 ================================= -NETWORK FILESYSTEM HELPER LIBRARY +Network Filesystem Helper Library ================================= .. Contents: @@ -37,22 +37,22 @@ into a common call framework. The following services are provided: - * Handles transparent huge pages (THPs). + * Handle folios that span multiple pages. - * Insulates the netfs from VM interface changes. + * Insulate the netfs from VM interface changes. - * Allows the netfs to arbitrarily split reads up into pieces, even ones that - don't match page sizes or page alignments and that may cross pages. + * Allow the netfs to arbitrarily split reads up into pieces, even ones that + don't match folio sizes or folio alignments and that may cross folios. - * Allows the netfs to expand a readahead request in both directions to meet - its needs. + * Allow the netfs to expand a readahead request in both directions to meet its + needs. - * Allows the netfs to partially fulfil a read, which will then be resubmitted. + * Allow the netfs to partially fulfil a read, which will then be resubmitted. - * Handles local caching, allowing cached data and server-read data to be + * Handle local caching, allowing cached data and server-read data to be interleaved for a single request. - * Handles clearing of bufferage that aren't on the server. + * Handle clearing of bufferage that aren't on the server. * Handle retrying of reads that failed, switching reads from the cache to the server as necessary. @@ -70,22 +70,22 @@ Read Helper Functions Three read helpers are provided:: - * void netfs_readahead(struct readahead_control *ractl, - const struct netfs_read_request_ops *ops, - void *netfs_priv);`` - * int netfs_readpage(struct file *file, - struct page *page, - const struct netfs_read_request_ops *ops, - void *netfs_priv); - * int netfs_write_begin(struct file *file, - struct address_space *mapping, - loff_t pos, - unsigned int len, - unsigned int flags, - struct page **_page, - void **_fsdata, - const struct netfs_read_request_ops *ops, - void *netfs_priv); + void netfs_readahead(struct readahead_control *ractl, + const struct netfs_read_request_ops *ops, + void *netfs_priv); + int netfs_readpage(struct file *file, + struct folio *folio, + const struct netfs_read_request_ops *ops, + void *netfs_priv); + int netfs_write_begin(struct file *file, + struct address_space *mapping, + loff_t pos, + unsigned int len, + unsigned int flags, + struct folio **_folio, + void **_fsdata, + const struct netfs_read_request_ops *ops, + void *netfs_priv); Each corresponds to a VM operation, with the addition of a couple of parameters for the use of the read helpers: @@ -103,8 +103,8 @@ Both of these values will be stored into the read request structure. For ->readahead() and ->readpage(), the network filesystem should just jump into the corresponding read helper; whereas for ->write_begin(), it may be a little more complicated as the network filesystem might want to flush -conflicting writes or track dirty data and needs to put the acquired page if an -error occurs after calling the helper. +conflicting writes or track dirty data and needs to put the acquired folio if +an error occurs after calling the helper. The helpers manage the read request, calling back into the network filesystem through the suppplied table of operations. Waits will be performed as @@ -253,7 +253,7 @@ through which it can issue requests and negotiate:: void (*issue_op)(struct netfs_read_subrequest *subreq); bool (*is_still_valid)(struct netfs_read_request *rreq); int (*check_write_begin)(struct file *file, loff_t pos, unsigned len, - struct page *page, void **_fsdata); + struct folio *folio, void **_fsdata); void (*done)(struct netfs_read_request *rreq); void (*cleanup)(struct address_space *mapping, void *netfs_priv); }; @@ -313,13 +313,14 @@ The operations are as follows: There is no return value; the netfs_subreq_terminated() function should be called to indicate whether or not the operation succeeded and how much data - it transferred. The filesystem also should not deal with setting pages + it transferred. The filesystem also should not deal with setting folios uptodate, unlocking them or dropping their refs - the helpers need to deal with this as they have to coordinate with copying to the local cache. - Note that the helpers have the pages locked, but not pinned. It is possible - to use the ITER_XARRAY iov iterator to refer to the range of the inode that - is being operated upon without the need to allocate large bvec tables. + Note that the helpers have the folios locked, but not pinned. It is + possible to use the ITER_XARRAY iov iterator to refer to the range of the + inode that is being operated upon without the need to allocate large bvec + tables. * ``is_still_valid()`` @@ -330,15 +331,15 @@ The operations are as follows: * ``check_write_begin()`` [Optional] This is called from the netfs_write_begin() helper once it has - allocated/grabbed the page to be modified to allow the filesystem to flush + allocated/grabbed the folio to be modified to allow the filesystem to flush conflicting state before allowing it to be modified. - It should return 0 if everything is now fine, -EAGAIN if the page should be + It should return 0 if everything is now fine, -EAGAIN if the folio should be regrabbed and any other error code to abort the operation. * ``done`` - [Optional] This is called after the pages in the request have all been + [Optional] This is called after the folios in the request have all been unlocked (and marked uptodate if applicable). * ``cleanup`` @@ -390,7 +391,7 @@ The read helpers work by the following general procedure: * If NETFS_SREQ_CLEAR_TAIL was set, a short read will be cleared to the end of the slice instead of reissuing. - * Once the data is read, the pages that have been fully read/cleared: + * Once the data is read, the folios that have been fully read/cleared: * Will be marked uptodate. @@ -398,11 +399,11 @@ The read helpers work by the following general procedure: * Unlocked - * Any pages that need writing to the cache will then have DIO writes issued. + * Any folios that need writing to the cache will then have DIO writes issued. * Synchronous operations will wait for reading to be complete. - * Writes to the cache will proceed asynchronously and the pages will have the + * Writes to the cache will proceed asynchronously and the folios will have the PG_fscache mark removed when that completes. * The request structures will be cleaned up when everything has completed. @@ -452,6 +453,9 @@ operation table looks like the following:: netfs_io_terminated_t term_func, void *term_func_priv); + int (*prepare_write)(struct netfs_cache_resources *cres, + loff_t *_start, size_t *_len, loff_t i_size); + int (*write)(struct netfs_cache_resources *cres, loff_t start_pos, struct iov_iter *iter, @@ -509,6 +513,14 @@ The methods defined in the table are: indicating whether the termination is definitely happening in the caller's context. + * ``prepare_write()`` + + [Required] Called to adjust a write to the cache and check that there is + sufficient space in the cache. The start and length values indicate the + size of the write that netfslib is proposing, and this can be adjusted by + the cache to respect DIO boundaries. The file size is passed for + information. + * ``write()`` [Required] Called to write to the cache. The start file offset is given @@ -525,4 +537,9 @@ not the read request structure as they could be used in other situations where there isn't a read request structure as well, such as writing dirty data to the cache. + +API Function Reference +====================== + .. kernel-doc:: include/linux/netfs.h +.. kernel-doc:: fs/netfs/read_helper.c diff --git a/fs/netfs/read_helper.c b/fs/netfs/read_helper.c index 9320a42dfaf9..7046f9bdd8dc 100644 --- a/fs/netfs/read_helper.c +++ b/fs/netfs/read_helper.c @@ -1008,8 +1008,8 @@ int netfs_readpage(struct file *file, } EXPORT_SYMBOL(netfs_readpage); -/** - * netfs_skip_folio_read - prep a folio for writing without reading first +/* + * Prepare a folio for writing without reading first * @folio: The folio being prepared * @pos: starting position for the write * @len: length of write
Adjust the netfslib docs in light of the foliation changes. Also un-kdoc-mark netfs_skip_folio_read() since it's internal and isn't part of the API. Signed-off-by: David Howells <dhowells@redhat.com> cc: Matthew Wilcox <willy@infradead.org> cc: linux-cachefs@redhat.com cc: linux-mm@kvack.org --- Documentation/filesystems/netfs_library.rst | 95 ++++++++++++++++----------- fs/netfs/read_helper.c | 4 + 2 files changed, 58 insertions(+), 41 deletions(-)