erofs has add file-backed mount support. In this scenario, only buffer
io is allowed. So we enhance the io mode by implementing the direct
io. Also, this can make the iov_iter (user buffer) interact with the
backed file's page cache directly.
Signed-off-by: Hongbo Li <lihongb...@huawei.com>
---
fs/erofs/data.c | 11 +++--
fs/erofs/fileio.c | 122 ++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 130 insertions(+), 3 deletions(-)
diff --git a/fs/erofs/data.c b/fs/erofs/data.c
index 0cd6b5c4df98..b5baff61be16 100644
--- a/fs/erofs/data.c
+++ b/fs/erofs/data.c
@@ -395,9 +395,14 @@ static ssize_t erofs_file_read_iter(struct kiocb *iocb,
struct iov_iter *to)
if (IS_DAX(inode))
return dax_iomap_rw(iocb, to, &erofs_iomap_ops);
#endif
- if ((iocb->ki_flags & IOCB_DIRECT) && inode->i_sb->s_bdev)
- return iomap_dio_rw(iocb, to, &erofs_iomap_ops,
- NULL, 0, NULL, 0);
+ if (iocb->ki_flags & IOCB_DIRECT) {
+ if (inode->i_sb->s_bdev)
+ return iomap_dio_rw(iocb, to, &erofs_iomap_ops,
+ NULL, 0, NULL, 0);
+ if (erofs_is_fileio_mode(EROFS_SB(inode->i_sb)))
+ return generic_file_read_iter(iocb, to);
+ }
+
return filemap_read(iocb, to, 0);
}
diff --git a/fs/erofs/fileio.c b/fs/erofs/fileio.c
index 33f8539dda4a..76ed16a8ee75 100644
--- a/fs/erofs/fileio.c
+++ b/fs/erofs/fileio.c
@@ -10,12 +10,17 @@ struct erofs_fileio_rq {
struct bio bio;
struct kiocb iocb;
struct super_block *sb;
+ ssize_t ret;
+ void *private;
};
struct erofs_fileio {
+ struct file *file;
struct erofs_map_blocks map;
struct erofs_map_dev dev;
struct erofs_fileio_rq *rq;
+ size_t total;
+ size_t done;
};
static void erofs_fileio_ki_complete(struct kiocb *iocb, long ret)
@@ -24,6 +29,7 @@ static void erofs_fileio_ki_complete(struct kiocb *iocb, long
ret)
container_of(iocb, struct erofs_fileio_rq, iocb);
struct folio_iter fi;
+ rq->ret = ret;
if (ret > 0) {
if (ret != rq->bio.bi_iter.bi_size) {
bio_advance(&rq->bio, ret);
@@ -43,6 +49,17 @@ static void erofs_fileio_ki_complete(struct kiocb *iocb,
long ret)
kfree(rq);
}
+static void erofs_fileio_end_io(struct bio *bio)
+{
+ struct erofs_fileio_rq *rq =
+ container_of(bio, struct erofs_fileio_rq, bio);
+ struct erofs_fileio *io = rq->private;
+
+ if (rq->ret > 0) {
+ io->done += rq->ret;
+ }
+}
+
static void erofs_fileio_rq_submit(struct erofs_fileio_rq *rq)
{
struct iov_iter iter;
@@ -189,7 +206,112 @@ static void erofs_fileio_readahead(struct
readahead_control *rac)
erofs_fileio_rq_submit(io.rq);
}
+static int erofs_fileio_scan_iter(struct erofs_fileio *io, struct kiocb *iocb,
+ struct iov_iter *iter)
+{
+ struct file *file = iocb->ki_filp;
+ struct inode *inode = file_inode(file);
+ struct erofs_map_blocks *map = &io->map;
+ struct iov_iter dest_iter = *iter;
+ unsigned int cur = 0, end = io->total, len;
+ loff_t pos = iocb->ki_pos;
+ int err = 0;
+
+ while (cur < end) {
+ /* submit the last fileio rq */
+ if (io->rq) {
+ erofs_fileio_rq_submit(io->rq);
+ io->rq = NULL;
+ }
+
+ if (!in_range(pos + cur, map->m_la, map->m_llen)) {
+ map->m_la = pos + cur;
+ map->m_llen = end - cur;
+ err = erofs_map_blocks(inode, map);
+ if (err)
+ break;
+ }
+
+ len = min_t(loff_t, map->m_llen, end - cur);
+ /* split the whole iter with (cur, len) */
+ dest_iter = *iter;
+ iov_iter_advance(&dest_iter, cur);
+ iov_iter_truncate(&dest_iter, len);
+ if (map->m_flags & EROFS_MAP_META) {
+ struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
+ void *src;
+
+ src = erofs_read_metabuf(&buf, inode->i_sb, map->m_pa,
EROFS_KMAP);
+ if (IS_ERR(src)) {
+ err = PTR_ERR(src);
+ break;
+ }
+ if (copy_to_iter(src, len, &dest_iter) != len) {
+ erofs_put_metabuf(&buf);
+ err = -EIO;
+ break;
+ }
+ erofs_put_metabuf(&buf);
+ io->done += len;
+ } else if (!(map->m_flags & EROFS_MAP_MAPPED)) {
+ iov_iter_zero(len, &dest_iter);
+ io->done += len;
+ } else {
+ io->dev = (struct erofs_map_dev) {
+ .m_pa = map->m_pa,
+ .m_deviceid = map->m_deviceid,
+ };
+ err = erofs_map_dev(inode->i_sb, &io->dev);
+ if (err)
+ break;
+ io->rq = erofs_fileio_rq_alloc(&io->dev);
+ io->rq->private = io;
+ io->rq->bio.bi_iter.bi_sector = io->dev.m_pa >>
SECTOR_SHIFT;
+ io->rq->bio.bi_end_io = erofs_fileio_end_io;
+
+ if (bio_iov_iter_get_pages(&io->rq->bio, &dest_iter)) {
+ err = -EIO;
+ break;
+ }
+ io->dev.m_pa += len;
+ }
+ cur += len;
+ }
+
+ return err;
+}
+
+static ssize_t erofs_fileio_direct_io(struct kiocb *iocb, struct iov_iter
*iter)
+{
+ struct file *file = iocb->ki_filp;
+ struct inode *inode = file_inode(file);
+ size_t i_size = i_size_read(inode);
+ struct erofs_fileio io = {};
+ int err = 0;
+
+ if (unlikely(iocb->ki_pos >= i_size))
+ return 0;
+
+ iter->count = min_t(size_t, iter->count,
+ max_t(size_t, 0, i_size - iocb->ki_pos));
+
+ io.total = iter->count;
+ if (!io.total)
+ return 0;
+
+ err = erofs_fileio_scan_iter(&io, iocb, iter);
+ if (err)
+ return err;
+ erofs_fileio_rq_submit(io.rq);
+ if (io.total != io.done)
+ return -EIO;
+
+ iov_iter_advance(iter, io.done);
+ return io.done;
+}
+
const struct address_space_operations erofs_fileio_aops = {
.read_folio = erofs_fileio_read_folio,
.readahead = erofs_fileio_readahead,
+ .direct_IO = erofs_fileio_direct_io,
};
--
2.34.1
