| Message ID | 92ae9f3333c9a7e66214568d08f45664261c899c.1715067055.git.ritesh.list@gmail.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | iomap: Optimize read_folio | expand |
On Tue, May 07, 2024 at 02:25:43PM +0530, Ritesh Harjani (IBM) wrote: > iomap_readpage_iter() handles "uptodate blocks" and "not uptodate blocks" > within a folio separately. This makes iomap_read_folio() to call into > ->iomap_begin() to request for extent mapping even though it might already > have an extent which is not fully processed. > This happens when we either have a large folio or with bs < ps. In these > cases we can have sub blocks which can be uptodate (say for e.g. due to > previous writes). With iomap_read_folio_iter(), this is handled more > efficiently by not calling ->iomap_begin() call until all the sub blocks > with the current folio are processed. > > iomap_read_folio_iter() handles multiple sub blocks within a given > folio but it's implementation logic is similar to how > iomap_readahead_iter() handles multiple folios within a single mapped > extent. Both of them iterate over a given range of folio/mapped extent > and call iomap_readpage_iter() for reading. > > Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com> > cc: Ojaswin Mujoo <ojaswin@linux.ibm.com> I like this improved changelog, it'e easier to understand why _read_folio_iter needs to exist. Reviewed-by: Darrick J. Wong <djwong@kernel.org> --D > --- > fs/iomap/buffered-io.c | 20 +++++++++++++++++++- > 1 file changed, 19 insertions(+), 1 deletion(-) > > diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c > index 9f79c82d1f73..a9bd74ee7870 100644 > --- a/fs/iomap/buffered-io.c > +++ b/fs/iomap/buffered-io.c > @@ -444,6 +444,24 @@ static loff_t iomap_readpage_iter(const struct iomap_iter *iter, > return pos - orig_pos + plen; > } > > +static loff_t iomap_read_folio_iter(const struct iomap_iter *iter, > + struct iomap_readpage_ctx *ctx) > +{ > + struct folio *folio = ctx->cur_folio; > + size_t offset = offset_in_folio(folio, iter->pos); > + loff_t length = min_t(loff_t, folio_size(folio) - offset, > + iomap_length(iter)); > + loff_t done, ret; > + > + for (done = 0; done < length; done += ret) { > + ret = iomap_readpage_iter(iter, ctx, done); > + if (ret <= 0) > + return ret; > + } > + > + return done; > +} > + > int iomap_read_folio(struct folio *folio, const struct iomap_ops *ops) > { > struct iomap_iter iter = { > @@ -459,7 +477,7 @@ int iomap_read_folio(struct folio *folio, const struct iomap_ops *ops) > trace_iomap_readpage(iter.inode, 1); > > while ((ret = iomap_iter(&iter, ops)) > 0) > - iter.processed = iomap_readpage_iter(&iter, &ctx, 0); > + iter.processed = iomap_read_folio_iter(&iter, &ctx); > > if (ret < 0) > folio_set_error(folio); > -- > 2.44.0 > >
Looks good:
Reviewed-by: Christoph Hellwig <hch@lst.de>
On Tue 07-05-24 14:25:43, Ritesh Harjani (IBM) wrote: > iomap_readpage_iter() handles "uptodate blocks" and "not uptodate blocks" > within a folio separately. This makes iomap_read_folio() to call into > ->iomap_begin() to request for extent mapping even though it might already > have an extent which is not fully processed. > This happens when we either have a large folio or with bs < ps. In these > cases we can have sub blocks which can be uptodate (say for e.g. due to > previous writes). With iomap_read_folio_iter(), this is handled more > efficiently by not calling ->iomap_begin() call until all the sub blocks > with the current folio are processed. > > iomap_read_folio_iter() handles multiple sub blocks within a given > folio but it's implementation logic is similar to how > iomap_readahead_iter() handles multiple folios within a single mapped > extent. Both of them iterate over a given range of folio/mapped extent > and call iomap_readpage_iter() for reading. > > Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com> > cc: Ojaswin Mujoo <ojaswin@linux.ibm.com> Looks good. Feel free to add: Reviewed-by: Jan Kara <jack@suse.cz> Honza > --- > fs/iomap/buffered-io.c | 20 +++++++++++++++++++- > 1 file changed, 19 insertions(+), 1 deletion(-) > > diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c > index 9f79c82d1f73..a9bd74ee7870 100644 > --- a/fs/iomap/buffered-io.c > +++ b/fs/iomap/buffered-io.c > @@ -444,6 +444,24 @@ static loff_t iomap_readpage_iter(const struct iomap_iter *iter, > return pos - orig_pos + plen; > } > > +static loff_t iomap_read_folio_iter(const struct iomap_iter *iter, > + struct iomap_readpage_ctx *ctx) > +{ > + struct folio *folio = ctx->cur_folio; > + size_t offset = offset_in_folio(folio, iter->pos); > + loff_t length = min_t(loff_t, folio_size(folio) - offset, > + iomap_length(iter)); > + loff_t done, ret; > + > + for (done = 0; done < length; done += ret) { > + ret = iomap_readpage_iter(iter, ctx, done); > + if (ret <= 0) > + return ret; > + } > + > + return done; > +} > + > int iomap_read_folio(struct folio *folio, const struct iomap_ops *ops) > { > struct iomap_iter iter = { > @@ -459,7 +477,7 @@ int iomap_read_folio(struct folio *folio, const struct iomap_ops *ops) > trace_iomap_readpage(iter.inode, 1); > > while ((ret = iomap_iter(&iter, ops)) > 0) > - iter.processed = iomap_readpage_iter(&iter, &ctx, 0); > + iter.processed = iomap_read_folio_iter(&iter, &ctx); > > if (ret < 0) > folio_set_error(folio); > -- > 2.44.0 >
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c index 9f79c82d1f73..a9bd74ee7870 100644 --- a/fs/iomap/buffered-io.c +++ b/fs/iomap/buffered-io.c @@ -444,6 +444,24 @@ static loff_t iomap_readpage_iter(const struct iomap_iter *iter, return pos - orig_pos + plen; } +static loff_t iomap_read_folio_iter(const struct iomap_iter *iter, + struct iomap_readpage_ctx *ctx) +{ + struct folio *folio = ctx->cur_folio; + size_t offset = offset_in_folio(folio, iter->pos); + loff_t length = min_t(loff_t, folio_size(folio) - offset, + iomap_length(iter)); + loff_t done, ret; + + for (done = 0; done < length; done += ret) { + ret = iomap_readpage_iter(iter, ctx, done); + if (ret <= 0) + return ret; + } + + return done; +} + int iomap_read_folio(struct folio *folio, const struct iomap_ops *ops) { struct iomap_iter iter = { @@ -459,7 +477,7 @@ int iomap_read_folio(struct folio *folio, const struct iomap_ops *ops) trace_iomap_readpage(iter.inode, 1); while ((ret = iomap_iter(&iter, ops)) > 0) - iter.processed = iomap_readpage_iter(&iter, &ctx, 0); + iter.processed = iomap_read_folio_iter(&iter, &ctx); if (ret < 0) folio_set_error(folio);
iomap_readpage_iter() handles "uptodate blocks" and "not uptodate blocks" within a folio separately. This makes iomap_read_folio() to call into ->iomap_begin() to request for extent mapping even though it might already have an extent which is not fully processed. This happens when we either have a large folio or with bs < ps. In these cases we can have sub blocks which can be uptodate (say for e.g. due to previous writes). With iomap_read_folio_iter(), this is handled more efficiently by not calling ->iomap_begin() call until all the sub blocks with the current folio are processed. iomap_read_folio_iter() handles multiple sub blocks within a given folio but it's implementation logic is similar to how iomap_readahead_iter() handles multiple folios within a single mapped extent. Both of them iterate over a given range of folio/mapped extent and call iomap_readpage_iter() for reading. Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com> cc: Ojaswin Mujoo <ojaswin@linux.ibm.com> --- fs/iomap/buffered-io.c | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-) -- 2.44.0