| Message ID | 20240328163424.2781320-10-dhowells@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | netfs, afs, 9p, cifs: Rework netfs to use ->writepages() to copy to cache | expand |
On Thu, 2024-03-28 at 16:34 +0000, David Howells wrote: > Implement a replacement for launder_folio. The key feature of > invalidate_inode_pages2() is that it locks each folio individually, unmaps > it to prevent mmap'd accesses interfering and calls the ->launder_folio() > address_space op to flush it. This has problems: firstly, each folio is > written individually as one or more small writes; secondly, adjacent folios > cannot be added so easily into the laundry; thirdly, it's yet another op to > implement. > > Instead, use the invalidate lock to cause anyone wanting to add a folio to > the inode to wait, then unmap all the folios if we have mmaps, then, > conditionally, use ->writepages() to flush any dirty data back and then > discard all pages. > > The invalidate lock prevents ->read_iter(), ->write_iter() and faulting > through mmap all from adding pages for the duration. > > Signed-off-by: David Howells <dhowells@redhat.com> > cc: Matthew Wilcox <willy@infradead.org> > cc: Miklos Szeredi <miklos@szeredi.hu> > cc: Trond Myklebust <trond.myklebust@hammerspace.com> > cc: Christoph Hellwig <hch@lst.de> > cc: Andrew Morton <akpm@linux-foundation.org> > cc: Alexander Viro <viro@zeniv.linux.org.uk> > cc: Christian Brauner <brauner@kernel.org> > cc: Jeff Layton <jlayton@kernel.org> > cc: linux-mm@kvack.org > cc: linux-fsdevel@vger.kernel.org > cc: netfs@lists.linux.dev > cc: v9fs@lists.linux.dev > cc: linux-afs@lists.infradead.org > cc: ceph-devel@vger.kernel.org > cc: linux-cifs@vger.kernel.org > cc: linux-nfs@vger.kernel.org > cc: devel@lists.orangefs.org > --- > include/linux/pagemap.h | 1 + > mm/filemap.c | 46 +++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 47 insertions(+) > > diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h > index 2df35e65557d..4eb3d4177a53 100644 > --- a/include/linux/pagemap.h > +++ b/include/linux/pagemap.h > @@ -40,6 +40,7 @@ int filemap_fdatawait_keep_errors(struct address_space *mapping); > int filemap_fdatawait_range(struct address_space *, loff_t lstart, loff_t lend); > int filemap_fdatawait_range_keep_errors(struct address_space *mapping, > loff_t start_byte, loff_t end_byte); > +int filemap_invalidate_inode(struct inode *inode, bool flush); > > static inline int filemap_fdatawait(struct address_space *mapping) > { > diff --git a/mm/filemap.c b/mm/filemap.c > index 25983f0f96e3..087f685107a5 100644 > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -4134,6 +4134,52 @@ bool filemap_release_folio(struct folio *folio, gfp_t gfp) > } > EXPORT_SYMBOL(filemap_release_folio); > > +/** > + * filemap_invalidate_inode - Invalidate/forcibly write back an inode's pagecache > + * @inode: The inode to flush > + * @flush: Set to write back rather than simply invalidate. > + * > + * Invalidate all the folios on an inode, possibly writing them back first. > + * Whilst the operation is undertaken, the invalidate lock is held to prevent > + * new folios from being installed. > + */ > +int filemap_invalidate_inode(struct inode *inode, bool flush) > +{ > + struct address_space *mapping = inode->i_mapping; > + > + if (!mapping || !mapping->nrpages) > + goto out; > + > + /* Prevent new folios from being added to the inode. */ > + filemap_invalidate_lock(mapping); > + > + if (!mapping->nrpages) > + goto unlock; > + > + unmap_mapping_pages(mapping, 0, ULONG_MAX, false); > + > + /* Write back the data if we're asked to. */ > + if (flush) { > + struct writeback_control wbc = { > + .sync_mode = WB_SYNC_ALL, > + .nr_to_write = LONG_MAX, > + .range_start = 0, > + .range_end = LLONG_MAX, > + }; > + > + filemap_fdatawrite_wbc(mapping, &wbc); > + } > + > + /* Wait for writeback to complete on all folios and discard. */ > + truncate_inode_pages_range(mapping, 0, LLONG_MAX); > + > +unlock: > + filemap_invalidate_unlock(mapping); > +out: > + return filemap_check_errors(mapping); > +} > +EXPORT_SYMBOL(filemap_invalidate_inode); > + > #ifdef CONFIG_CACHESTAT_SYSCALL > /** > * filemap_cachestat() - compute the page cache statistics of a mapping > > I'd have liked to have seen the first caller of this function too.
Jeff Layton <jlayton@kernel.org> wrote:
> I'd have liked to have seen the first caller of this function too.
Looking again at my code, I also need to make netfs_unbuffered_write_iter()
use this function too. I missed it before because that wasn't calling
invalidate_inode_pages2_range() directly, but rather going through
kiocb_invalidate_pages().
So I'll add those changes into this patch to give you a first caller. I also
then need to make filemap_invalidate_inode() take a byte range.
David
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 2df35e65557d..4eb3d4177a53 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -40,6 +40,7 @@ int filemap_fdatawait_keep_errors(struct address_space *mapping); int filemap_fdatawait_range(struct address_space *, loff_t lstart, loff_t lend); int filemap_fdatawait_range_keep_errors(struct address_space *mapping, loff_t start_byte, loff_t end_byte); +int filemap_invalidate_inode(struct inode *inode, bool flush); static inline int filemap_fdatawait(struct address_space *mapping) { diff --git a/mm/filemap.c b/mm/filemap.c index 25983f0f96e3..087f685107a5 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -4134,6 +4134,52 @@ bool filemap_release_folio(struct folio *folio, gfp_t gfp) } EXPORT_SYMBOL(filemap_release_folio); +/** + * filemap_invalidate_inode - Invalidate/forcibly write back an inode's pagecache + * @inode: The inode to flush + * @flush: Set to write back rather than simply invalidate. + * + * Invalidate all the folios on an inode, possibly writing them back first. + * Whilst the operation is undertaken, the invalidate lock is held to prevent + * new folios from being installed. + */ +int filemap_invalidate_inode(struct inode *inode, bool flush) +{ + struct address_space *mapping = inode->i_mapping; + + if (!mapping || !mapping->nrpages) + goto out; + + /* Prevent new folios from being added to the inode. */ + filemap_invalidate_lock(mapping); + + if (!mapping->nrpages) + goto unlock; + + unmap_mapping_pages(mapping, 0, ULONG_MAX, false); + + /* Write back the data if we're asked to. */ + if (flush) { + struct writeback_control wbc = { + .sync_mode = WB_SYNC_ALL, + .nr_to_write = LONG_MAX, + .range_start = 0, + .range_end = LLONG_MAX, + }; + + filemap_fdatawrite_wbc(mapping, &wbc); + } + + /* Wait for writeback to complete on all folios and discard. */ + truncate_inode_pages_range(mapping, 0, LLONG_MAX); + +unlock: + filemap_invalidate_unlock(mapping); +out: + return filemap_check_errors(mapping); +} +EXPORT_SYMBOL(filemap_invalidate_inode); + #ifdef CONFIG_CACHESTAT_SYSCALL /** * filemap_cachestat() - compute the page cache statistics of a mapping
Implement a replacement for launder_folio. The key feature of invalidate_inode_pages2() is that it locks each folio individually, unmaps it to prevent mmap'd accesses interfering and calls the ->launder_folio() address_space op to flush it. This has problems: firstly, each folio is written individually as one or more small writes; secondly, adjacent folios cannot be added so easily into the laundry; thirdly, it's yet another op to implement. Instead, use the invalidate lock to cause anyone wanting to add a folio to the inode to wait, then unmap all the folios if we have mmaps, then, conditionally, use ->writepages() to flush any dirty data back and then discard all pages. The invalidate lock prevents ->read_iter(), ->write_iter() and faulting through mmap all from adding pages for the duration. Signed-off-by: David Howells <dhowells@redhat.com> cc: Matthew Wilcox <willy@infradead.org> cc: Miklos Szeredi <miklos@szeredi.hu> cc: Trond Myklebust <trond.myklebust@hammerspace.com> cc: Christoph Hellwig <hch@lst.de> cc: Andrew Morton <akpm@linux-foundation.org> cc: Alexander Viro <viro@zeniv.linux.org.uk> cc: Christian Brauner <brauner@kernel.org> cc: Jeff Layton <jlayton@kernel.org> cc: linux-mm@kvack.org cc: linux-fsdevel@vger.kernel.org cc: netfs@lists.linux.dev cc: v9fs@lists.linux.dev cc: linux-afs@lists.infradead.org cc: ceph-devel@vger.kernel.org cc: linux-cifs@vger.kernel.org cc: linux-nfs@vger.kernel.org cc: devel@lists.orangefs.org --- include/linux/pagemap.h | 1 + mm/filemap.c | 46 +++++++++++++++++++++++++++++++++++++++++ 2 files changed, 47 insertions(+)