With that, the direct_IO address space operation can be all but
eliminated: only a dummy remains which indicates that the filesystem
supports direct I/O.
Signed-off-by: Andreas Gruenbacher <agrue...@redhat.com>
---
fs/gfs2/aops.c | 92 +------------------------------
fs/gfs2/bmap.c | 14 ++++-
fs/gfs2/file.c | 171 +++++++++++++++++++++++++++++++++++++++++++++++++++++----
3 files changed, 174 insertions(+), 103 deletions(-)
diff --git a/fs/gfs2/aops.c b/fs/gfs2/aops.c
index 3d9633175aa8..d676ee63ab2b 100644
--- a/fs/gfs2/aops.c
+++ b/fs/gfs2/aops.c
@@ -84,12 +84,6 @@ static int gfs2_get_block_noalloc(struct inode *inode,
sector_t lblock,
return 0;
}
-static int gfs2_get_block_direct(struct inode *inode, sector_t lblock,
- struct buffer_head *bh_result, int create)
-{
- return gfs2_block_map(inode, lblock, bh_result, 0);
-}
-
/**
* gfs2_writepage_common - Common bits of writepage
* @page: The page to be written
@@ -1021,94 +1015,12 @@ static void gfs2_invalidatepage(struct page *page,
unsigned int offset,
try_to_release_page(page, 0);
}
-/**
- * gfs2_ok_for_dio - check that dio is valid on this file
- * @ip: The inode
- * @offset: The offset at which we are reading or writing
- *
- * Returns: 0 (to ignore the i/o request and thus fall back to buffered i/o)
- * 1 (to accept the i/o request)
- */
-static int gfs2_ok_for_dio(struct gfs2_inode *ip, loff_t offset)
-{
- /*
- * Should we return an error here? I can't see that O_DIRECT for
- * a stuffed file makes any sense. For now we'll silently fall
- * back to buffered I/O
- */
- if (gfs2_is_stuffed(ip))
- return 0;
-
- if (offset >= i_size_read(&ip->i_inode))
- return 0;
- return 1;
-}
-
-
-
static ssize_t gfs2_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
{
- struct file *file = iocb->ki_filp;
- struct inode *inode = file->f_mapping->host;
- struct address_space *mapping = inode->i_mapping;
- struct gfs2_inode *ip = GFS2_I(inode);
- loff_t offset = iocb->ki_pos;
- struct gfs2_holder gh;
- int rv;
-
/*
- * Deferred lock, even if its a write, since we do no allocation
- * on this path. All we need change is atime, and this lock mode
- * ensures that other nodes have flushed their buffered read caches
- * (i.e. their page cache entries for this inode). We do not,
- * unfortunately have the option of only flushing a range like
- * the VFS does.
+ * We just need the method present so that open/fcntl allow direct I/O.
*/
- gfs2_holder_init(ip->i_gl, LM_ST_DEFERRED, 0, &gh);
- rv = gfs2_glock_nq(&gh);
- if (rv)
- goto out_uninit;
- rv = gfs2_ok_for_dio(ip, offset);
- if (rv != 1)
- goto out; /* dio not valid, fall back to buffered i/o */
-
- /*
- * Now since we are holding a deferred (CW) lock at this point, you
- * might be wondering why this is ever needed. There is a case however
- * where we've granted a deferred local lock against a cached exclusive
- * glock. That is ok provided all granted local locks are deferred, but
- * it also means that it is possible to encounter pages which are
- * cached and possibly also mapped. So here we check for that and sort
- * them out ahead of the dio. The glock state machine will take care of
- * everything else.
- *
- * If in fact the cached glock state (gl->gl_state) is deferred (CW) in
- * the first place, mapping->nr_pages will always be zero.
- */
- if (mapping->nrpages) {
- loff_t lstart = offset & ~(PAGE_SIZE - 1);
- loff_t len = iov_iter_count(iter);
- loff_t end = PAGE_ALIGN(offset + len) - 1;
-
- rv = 0;
- if (len == 0)
- goto out;
- if (test_and_clear_bit(GIF_SW_PAGED, &ip->i_flags))
- unmap_shared_mapping_range(ip->i_inode.i_mapping,
offset, len);
- rv = filemap_write_and_wait_range(mapping, lstart, end);
- if (rv)
- goto out;
- if (iov_iter_rw(iter) == WRITE)
- truncate_inode_pages_range(mapping, lstart, end);
- }
-
- rv = __blockdev_direct_IO(iocb, inode, inode->i_sb->s_bdev, iter,
- gfs2_get_block_direct, NULL, NULL, 0);
-out:
- gfs2_glock_dq(&gh);
-out_uninit:
- gfs2_holder_uninit(&gh);
- return rv;
+ return -EINVAL;
}
/**
diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c
index b6ee5252c014..fcafad122392 100644
--- a/fs/gfs2/bmap.c
+++ b/fs/gfs2/bmap.c
@@ -805,6 +805,9 @@ static int gfs2_iomap_get(struct inode *inode, loff_t pos,
loff_t length,
iomap->length = hole_size(inode, lblock, mp);
else
iomap->length = size - pos;
+ } else if (!(flags & IOMAP_WRITE)) {
+ if (height == ip->i_height)
+ iomap->length = hole_size(inode, lblock, mp);
}
/* FIXME: Should we limit iomap->length to the maximum allocation size
* here according to how gfs2_iomap_alloc allocates blocks? */
@@ -949,7 +952,14 @@ static int gfs2_iomap_begin(struct inode *inode, loff_t
pos, loff_t length,
trace_gfs2_iomap_start(ip, pos, length, flags);
if (flags & IOMAP_WRITE) {
- ret = gfs2_iomap_begin_write(inode, pos, length, flags, iomap);
+ if (flags & IOMAP_DIRECT) {
+ ret = gfs2_iomap_get(inode, pos, length, flags, iomap,
&mp);
+ release_metapath(&mp);
+ if (iomap->type != IOMAP_MAPPED)
+ ret = -ENOTBLK;
+ } else {
+ ret = gfs2_iomap_begin_write(inode, pos, length, flags,
iomap);
+ }
} else {
ret = gfs2_iomap_get(inode, pos, length, flags, iomap, &mp);
release_metapath(&mp);
@@ -1020,7 +1030,7 @@ static int gfs2_iomap_end(struct inode *inode, loff_t
pos, loff_t length,
struct gfs2_sbd *sdp = GFS2_SB(inode);
struct gfs2_trans *tr = current->journal_info;
- if (!(flags & IOMAP_WRITE))
+ if ((flags & (IOMAP_WRITE | IOMAP_DIRECT)) != IOMAP_WRITE)
return 0;
gfs2_ordered_add_inode(ip);
diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c
index d1b54e781577..a6c54a4f46fd 100644
--- a/fs/gfs2/file.c
+++ b/fs/gfs2/file.c
@@ -690,6 +690,122 @@ static int gfs2_fsync(struct file *file, loff_t start,
loff_t end,
return ret ? ret : ret1;
}
+static ssize_t gfs2_file_direct_read(struct kiocb *iocb, struct iov_iter *to)
+{
+ struct file *file = iocb->ki_filp;
+ struct gfs2_inode *ip = GFS2_I(file->f_mapping->host);
+ size_t count = iov_iter_count(to);
+ struct gfs2_holder gh;
+ ssize_t ret;
+
+ if (!count)
+ return 0; /* skip atime */
+
+ gfs2_holder_init(ip->i_gl, LM_ST_DEFERRED, 0, &gh);
+ ret = gfs2_glock_nq(&gh);
+ if (ret)
+ goto out_uninit;
+
+ /* fall back to buffered I/O for stuffed files */
+ ret = -ENOTBLK;
+ if (gfs2_is_stuffed(ip))
+ goto out;
+
+ ret = iomap_dio_rw(iocb, to, &gfs2_iomap_ops, NULL);
+
+out:
+ gfs2_glock_dq(&gh);
+out_uninit:
+ gfs2_holder_uninit(&gh);
+ return ret;
+}
+
+static ssize_t gfs2_file_direct_write(struct kiocb *iocb, struct iov_iter
*from)
+{
+ struct file *file = iocb->ki_filp;
+ struct inode *inode = file->f_mapping->host;
+ struct address_space *mapping = inode->i_mapping;
+ struct gfs2_inode *ip = GFS2_I(inode);
+ size_t len = iov_iter_count(from);
+ loff_t offset = iocb->ki_pos;
+ struct gfs2_holder gh;
+ ssize_t ret;
+
+ /*
+ * Deferred lock, even if its a write, since we do no allocation on
+ * this path. All we need to change is the atime, and this lock mode
+ * ensures that other nodes have flushed their buffered read caches
+ * (i.e. their page cache entries for this inode). We do not,
+ * unfortunately, have the option of only flushing a range like the
+ * VFS does.
+ */
+ gfs2_holder_init(ip->i_gl, LM_ST_DEFERRED, 0, &gh);
+ ret = gfs2_glock_nq(&gh);
+ if (ret)
+ goto out_uninit;
+
+ /* Silently fall back to buffered I/O for stuffed files */
+ if (gfs2_is_stuffed(ip))
+ goto out;
+
+ /* Silently fall back to buffered I/O when writing beyond EOF */
+ if (offset + len > i_size_read(&ip->i_inode))
+ goto out;
+
+ /*
+ * Now since we are holding a deferred (CW) lock at this point, you
+ * might be wondering why this is ever needed. There is a case however
+ * where we've granted a deferred local lock against a cached exclusive
+ * glock. That is ok provided all granted local locks are deferred, but
+ * it also means that it is possible to encounter pages which are
+ * cached and possibly also mapped. So here we check for that and sort
+ * them out ahead of the dio. The glock state machine will take care of
+ * everything else.
+ *
+ * If in fact the cached glock state (gl->gl_state) is deferred (CW) in
+ * the first place, mapping->nr_pages will always be zero.
+ */
+ if (mapping->nrpages) {
+ loff_t lstart = offset & ~(PAGE_SIZE - 1);
+ loff_t len = iov_iter_count(from);
+ loff_t end = PAGE_ALIGN(offset + len) - 1;
+
+ ret = 0;
+ if (len == 0)
+ goto out;
+ if (test_and_clear_bit(GIF_SW_PAGED, &ip->i_flags))
+ unmap_shared_mapping_range(ip->i_inode.i_mapping,
offset, len);
+ ret = filemap_write_and_wait_range(mapping, lstart, end);
+ if (ret)
+ goto out;
+ if (iov_iter_rw(from) == WRITE)
+ truncate_inode_pages_range(mapping, lstart, end);
+ }
+
+ ret = iomap_dio_rw(iocb, from, &gfs2_iomap_ops, NULL);
+
+out:
+ gfs2_glock_dq(&gh);
+out_uninit:
+ gfs2_holder_uninit(&gh);
+ return ret;
+}
+
+static ssize_t gfs2_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
+{
+ ssize_t ret;
+
+ if (iocb->ki_flags & IOCB_DIRECT) {
+ ret = gfs2_file_direct_read(iocb, to);
+ if (likely(ret != -ENOTBLK))
+ goto out;
+ iocb->ki_flags &= ~IOCB_DIRECT;
+ }
+ ret = generic_file_read_iter(iocb, to);
+out:
+ return ret;
+}
+
/**
* gfs2_file_write_iter - Perform a write to a file
* @iocb: The io context
@@ -707,7 +823,7 @@ static ssize_t gfs2_file_write_iter(struct kiocb *iocb,
struct iov_iter *from)
struct file *file = iocb->ki_filp;
struct inode *inode = file->f_mapping->host;
struct gfs2_inode *ip = GFS2_I(inode);
- ssize_t ret;
+ ssize_t written = 0, ret;
ret = gfs2_rsqa_alloc(ip);
if (ret)
@@ -724,9 +840,6 @@ static ssize_t gfs2_file_write_iter(struct kiocb *iocb,
struct iov_iter *from)
gfs2_glock_dq_uninit(&gh);
}
- if (iocb->ki_flags & IOCB_DIRECT)
- return generic_file_write_iter(iocb, from);
-
inode_lock(inode);
ret = generic_write_checks(iocb, from);
if (ret <= 0)
@@ -743,19 +856,55 @@ static ssize_t gfs2_file_write_iter(struct kiocb *iocb,
struct iov_iter *from)
/* We can write back this queue in page reclaim */
current->backing_dev_info = inode_to_bdi(inode);
- ret = iomap_file_buffered_write(iocb, from, &gfs2_iomap_ops);
+ if (iocb->ki_flags & IOCB_DIRECT) {
+ struct address_space *mapping = file->f_mapping;
+ loff_t pos, endbyte;
+ ssize_t buffered;
- current->backing_dev_info = NULL;
+ written = gfs2_file_direct_write(iocb, from);
+ if (written < 0 || !iov_iter_count(from))
+ goto out2;
+
+ ret = iomap_file_buffered_write(iocb, from, &gfs2_iomap_ops);
+ if (unlikely(ret < 0))
+ goto out2;
+ buffered = ret;
+ /*
+ * We need to ensure that the page cache pages are written to
+ * disk and invalidated to preserve the expected O_DIRECT
+ * semantics.
+ */
+ pos = iocb->ki_pos;
+ endbyte = pos + buffered - 1;
+ ret = filemap_write_and_wait_range(mapping, pos, endbyte);
+ if (!ret) {
+ iocb->ki_pos += buffered;
+ written += buffered;
+ invalidate_mapping_pages(mapping,
+ pos >> PAGE_SHIFT,
+ endbyte >> PAGE_SHIFT);
+ } else {
+ /*
+ * We don't know how much we wrote, so just return
+ * the number of bytes which were direct-written
+ */
+ }
+ } else {
+ ret = iomap_file_buffered_write(iocb, from, &gfs2_iomap_ops);
+ if (likely(ret > 0))
+ iocb->ki_pos += ret;
+ }
+
+out2:
+ current->backing_dev_info = NULL;
out:
inode_unlock(inode);
if (likely(ret > 0)) {
- iocb->ki_pos += ret;
-
/* Handle various SYNC-type writes */
ret = generic_write_sync(iocb, ret);
}
- return ret;
+ return written ? written : ret;
}
static int fallocate_chunk(struct inode *inode, loff_t offset, loff_t len,
@@ -1158,7 +1307,7 @@ static int gfs2_flock(struct file *file, int cmd, struct
file_lock *fl)
const struct file_operations gfs2_file_fops = {
.llseek = gfs2_llseek,
- .read_iter = generic_file_read_iter,
+ .read_iter = gfs2_file_read_iter,
.write_iter = gfs2_file_write_iter,
.unlocked_ioctl = gfs2_ioctl,
.mmap = gfs2_mmap,
@@ -1188,7 +1337,7 @@ const struct file_operations gfs2_dir_fops = {
const struct file_operations gfs2_file_fops_nolock = {
.llseek = gfs2_llseek,
- .read_iter = generic_file_read_iter,
+ .read_iter = gfs2_file_read_iter,
.write_iter = gfs2_file_write_iter,
.unlocked_ioctl = gfs2_ioctl,
.mmap = gfs2_mmap,
--
2.14.3
