| Message ID | 20221231150919.659533-6-agruenba@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Turn iomap_page_ops into iomap_folio_ops | expand |
On Sat, Dec 31, 2022 at 04:09:15PM +0100, Andreas Gruenbacher wrote: > Change the iomap ->page_prepare() handler to get and return a locked > folio instead of doing that in iomap_write_begin(). This allows to > recover from out-of-memory situations in ->page_prepare(), which > eliminates the corresponding error handling code in iomap_write_begin(). > The ->put_folio() handler now also isn't called with NULL as the folio > value anymore. > > Filesystems are expected to use the iomap_get_folio() helper for getting > locked folios in their ->page_prepare() handlers. > > Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com> This patchset makes the page ops make a lot more sense to me now. I very much like the way that the new ->get_folio ->put_folio functions split the responsibilities for setting up the page cach write and tearing it down. Thank you for cleaning this up. :) (I would still like hch or willy to take a second look at this, however.) Reviewed-by: Darrick J. Wong <djwong@kernel.org> --D > --- > fs/gfs2/bmap.c | 21 +++++++++++++-------- > fs/iomap/buffered-io.c | 17 ++++++----------- > include/linux/iomap.h | 9 +++++---- > 3 files changed, 24 insertions(+), 23 deletions(-) > > diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c > index 0c041459677b..41349e09558b 100644 > --- a/fs/gfs2/bmap.c > +++ b/fs/gfs2/bmap.c > @@ -956,15 +956,25 @@ static int __gfs2_iomap_get(struct inode *inode, loff_t pos, loff_t length, > goto out; > } > > -static int gfs2_iomap_page_prepare(struct inode *inode, loff_t pos, > - unsigned len) > +static struct folio * > +gfs2_iomap_page_prepare(struct iomap_iter *iter, loff_t pos, unsigned len) > { > + struct inode *inode = iter->inode; > unsigned int blockmask = i_blocksize(inode) - 1; > struct gfs2_sbd *sdp = GFS2_SB(inode); > unsigned int blocks; > + struct folio *folio; > + int status; > > blocks = ((pos & blockmask) + len + blockmask) >> inode->i_blkbits; > - return gfs2_trans_begin(sdp, RES_DINODE + blocks, 0); > + status = gfs2_trans_begin(sdp, RES_DINODE + blocks, 0); > + if (status) > + return ERR_PTR(status); > + > + folio = iomap_get_folio(iter, pos); > + if (IS_ERR(folio)) > + gfs2_trans_end(sdp); > + return folio; > } > > static void gfs2_iomap_put_folio(struct inode *inode, loff_t pos, > @@ -974,11 +984,6 @@ static void gfs2_iomap_put_folio(struct inode *inode, loff_t pos, > struct gfs2_inode *ip = GFS2_I(inode); > struct gfs2_sbd *sdp = GFS2_SB(inode); > > - if (!folio) { > - gfs2_trans_end(sdp); > - return; > - } > - > if (!gfs2_is_stuffed(ip)) > gfs2_page_add_databufs(ip, &folio->page, offset_in_page(pos), > copied); > diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c > index b84838d2b5d8..7decd8cdc755 100644 > --- a/fs/iomap/buffered-io.c > +++ b/fs/iomap/buffered-io.c > @@ -609,7 +609,7 @@ static void iomap_put_folio(struct iomap_iter *iter, loff_t pos, size_t ret, > > if (page_ops && page_ops->put_folio) { > page_ops->put_folio(iter->inode, pos, ret, folio); > - } else if (folio) { > + } else { > folio_unlock(folio); > folio_put(folio); > } > @@ -642,17 +642,12 @@ static int iomap_write_begin(struct iomap_iter *iter, loff_t pos, > if (!mapping_large_folio_support(iter->inode->i_mapping)) > len = min_t(size_t, len, PAGE_SIZE - offset_in_page(pos)); > > - if (page_ops && page_ops->page_prepare) { > - status = page_ops->page_prepare(iter->inode, pos, len); > - if (status) > - return status; > - } > - > - folio = iomap_get_folio(iter, pos); > - if (IS_ERR(folio)) { > - iomap_put_folio(iter, pos, 0, NULL); > + if (page_ops && page_ops->page_prepare) > + folio = page_ops->page_prepare(iter, pos, len); > + else > + folio = iomap_get_folio(iter, pos); > + if (IS_ERR(folio)) > return PTR_ERR(folio); > - } > > /* > * Now we have a locked folio, before we do anything with it we need to > diff --git a/include/linux/iomap.h b/include/linux/iomap.h > index e5732cc5716b..87b5d0f8e578 100644 > --- a/include/linux/iomap.h > +++ b/include/linux/iomap.h > @@ -13,6 +13,7 @@ > struct address_space; > struct fiemap_extent_info; > struct inode; > +struct iomap_iter; > struct iomap_dio; > struct iomap_writepage_ctx; > struct iov_iter; > @@ -131,12 +132,12 @@ static inline bool iomap_inline_data_valid(const struct iomap *iomap) > * associated with them. > * > * When page_prepare succeeds, put_folio will always be called to do any > - * cleanup work necessary. In that put_folio call, @folio will be NULL if the > - * associated folio could not be obtained. When folio is not NULL, put_folio > - * is responsible for unlocking and putting the folio. > + * cleanup work necessary. put_folio is responsible for unlocking and putting > + * @folio. > */ > struct iomap_page_ops { > - int (*page_prepare)(struct inode *inode, loff_t pos, unsigned len); > + struct folio *(*page_prepare)(struct iomap_iter *iter, loff_t pos, > + unsigned len); > void (*put_folio)(struct inode *inode, loff_t pos, unsigned copied, > struct folio *folio); > > -- > 2.38.1 >
> + if (page_ops && page_ops->page_prepare) > + folio = page_ops->page_prepare(iter, pos, len); > + else > + folio = iomap_get_folio(iter, pos); > + if (IS_ERR(folio)) > return PTR_ERR(folio); I'd love to have a iomap_get_folio helper for this sequence so that we match iomap_put_folio. That would require renaming the current iomap_get_folio to __iomap_get_folio. Otherwise this looks good: Reviewed-by: Christoph Hellwig <hch@lst.de>
On Sun, Jan 8, 2023 at 6:29 PM Christoph Hellwig <hch@infradead.org> wrote: > > + if (page_ops && page_ops->page_prepare) > > + folio = page_ops->page_prepare(iter, pos, len); > > + else > > + folio = iomap_get_folio(iter, pos); > > + if (IS_ERR(folio)) > > return PTR_ERR(folio); > > I'd love to have a iomap_get_folio helper for this sequence so that > we match iomap_put_folio. That would require renaming the current > iomap_get_folio to __iomap_get_folio. That's the wrong way around though. iomap_get_folio() is exported to filesystems, so if at all, we should rename iomap_put_folio() which is a static function only used in the iomap code. I'll post an update. Thanks, Andreas
diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c index 0c041459677b..41349e09558b 100644 --- a/fs/gfs2/bmap.c +++ b/fs/gfs2/bmap.c @@ -956,15 +956,25 @@ static int __gfs2_iomap_get(struct inode *inode, loff_t pos, loff_t length, goto out; } -static int gfs2_iomap_page_prepare(struct inode *inode, loff_t pos, - unsigned len) +static struct folio * +gfs2_iomap_page_prepare(struct iomap_iter *iter, loff_t pos, unsigned len) { + struct inode *inode = iter->inode; unsigned int blockmask = i_blocksize(inode) - 1; struct gfs2_sbd *sdp = GFS2_SB(inode); unsigned int blocks; + struct folio *folio; + int status; blocks = ((pos & blockmask) + len + blockmask) >> inode->i_blkbits; - return gfs2_trans_begin(sdp, RES_DINODE + blocks, 0); + status = gfs2_trans_begin(sdp, RES_DINODE + blocks, 0); + if (status) + return ERR_PTR(status); + + folio = iomap_get_folio(iter, pos); + if (IS_ERR(folio)) + gfs2_trans_end(sdp); + return folio; } static void gfs2_iomap_put_folio(struct inode *inode, loff_t pos, @@ -974,11 +984,6 @@ static void gfs2_iomap_put_folio(struct inode *inode, loff_t pos, struct gfs2_inode *ip = GFS2_I(inode); struct gfs2_sbd *sdp = GFS2_SB(inode); - if (!folio) { - gfs2_trans_end(sdp); - return; - } - if (!gfs2_is_stuffed(ip)) gfs2_page_add_databufs(ip, &folio->page, offset_in_page(pos), copied); diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c index b84838d2b5d8..7decd8cdc755 100644 --- a/fs/iomap/buffered-io.c +++ b/fs/iomap/buffered-io.c @@ -609,7 +609,7 @@ static void iomap_put_folio(struct iomap_iter *iter, loff_t pos, size_t ret, if (page_ops && page_ops->put_folio) { page_ops->put_folio(iter->inode, pos, ret, folio); - } else if (folio) { + } else { folio_unlock(folio); folio_put(folio); } @@ -642,17 +642,12 @@ static int iomap_write_begin(struct iomap_iter *iter, loff_t pos, if (!mapping_large_folio_support(iter->inode->i_mapping)) len = min_t(size_t, len, PAGE_SIZE - offset_in_page(pos)); - if (page_ops && page_ops->page_prepare) { - status = page_ops->page_prepare(iter->inode, pos, len); - if (status) - return status; - } - - folio = iomap_get_folio(iter, pos); - if (IS_ERR(folio)) { - iomap_put_folio(iter, pos, 0, NULL); + if (page_ops && page_ops->page_prepare) + folio = page_ops->page_prepare(iter, pos, len); + else + folio = iomap_get_folio(iter, pos); + if (IS_ERR(folio)) return PTR_ERR(folio); - } /* * Now we have a locked folio, before we do anything with it we need to diff --git a/include/linux/iomap.h b/include/linux/iomap.h index e5732cc5716b..87b5d0f8e578 100644 --- a/include/linux/iomap.h +++ b/include/linux/iomap.h @@ -13,6 +13,7 @@ struct address_space; struct fiemap_extent_info; struct inode; +struct iomap_iter; struct iomap_dio; struct iomap_writepage_ctx; struct iov_iter; @@ -131,12 +132,12 @@ static inline bool iomap_inline_data_valid(const struct iomap *iomap) * associated with them. * * When page_prepare succeeds, put_folio will always be called to do any - * cleanup work necessary. In that put_folio call, @folio will be NULL if the - * associated folio could not be obtained. When folio is not NULL, put_folio - * is responsible for unlocking and putting the folio. + * cleanup work necessary. put_folio is responsible for unlocking and putting + * @folio. */ struct iomap_page_ops { - int (*page_prepare)(struct inode *inode, loff_t pos, unsigned len); + struct folio *(*page_prepare)(struct iomap_iter *iter, loff_t pos, + unsigned len); void (*put_folio)(struct inode *inode, loff_t pos, unsigned copied, struct folio *folio);
Change the iomap ->page_prepare() handler to get and return a locked folio instead of doing that in iomap_write_begin(). This allows to recover from out-of-memory situations in ->page_prepare(), which eliminates the corresponding error handling code in iomap_write_begin(). The ->put_folio() handler now also isn't called with NULL as the folio value anymore. Filesystems are expected to use the iomap_get_folio() helper for getting locked folios in their ->page_prepare() handlers. Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com> --- fs/gfs2/bmap.c | 21 +++++++++++++-------- fs/iomap/buffered-io.c | 17 ++++++----------- include/linux/iomap.h | 9 +++++---- 3 files changed, 24 insertions(+), 23 deletions(-)