[GFS2] Alter direct I/O path
As per comments received, alter the GFS2 direct I/O path so that
it uses the standard read functions "out of the box". Needs a
small change to one of the VFS functions. This reduces the size
of the code quite a lot and also removes the need for one new export.
Some more work remains to be done, but this is the bones of the
thing.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
diff --git a/fs/gfs2/ops_address.c b/fs/gfs2/ops_address.c
index 031270a..d33f6aa 100644
--- a/fs/gfs2/ops_address.c
+++ b/fs/gfs2/ops_address.c
@@ -589,8 +589,9 @@
return;
}
-static ssize_t gfs2_direct_IO_write(struct kiocb *iocb, const struct iovec *iov,
- loff_t offset, unsigned long nr_segs)
+static ssize_t gfs2_direct_IO(int rw, struct kiocb *iocb,
+ const struct iovec *iov, loff_t offset,
+ unsigned long nr_segs)
{
struct file *file = iocb->ki_filp;
struct inode *inode = file->f_mapping->host;
@@ -598,8 +599,10 @@
struct gfs2_holder gh;
int rv;
+ if (rw == READ)
+ mutex_lock(&inode->i_mutex);
/*
- * Shared lock, even though its write, since we do no allocation
+ * Shared lock, even if its a write, since we do no allocation
* on this path. All we need change is atime.
*/
gfs2_holder_init(ip->i_gl, LM_ST_SHARED, GL_ATIME, &gh);
@@ -607,6 +610,9 @@
if (rv)
goto out;
+ if (offset > i_size_read(inode))
+ goto out;
+
/*
* Should we return an error here? I can't see that O_DIRECT for
* a journaled file makes any sense. For now we'll silently fall
@@ -619,48 +625,20 @@
if (gfs2_is_stuffed(ip))
goto out;
- rv = __blockdev_direct_IO(WRITE, iocb, inode, inode->i_sb->s_bdev,
- iov, offset, nr_segs, gfs2_get_block,
- NULL, DIO_OWN_LOCKING);
+ rv = blockdev_direct_IO_own_locking(rw, iocb, inode,
+ inode->i_sb->s_bdev,
+ iov, offset, nr_segs,
+ gfs2_get_block, NULL);
out:
gfs2_glock_dq_m(1, &gh);
gfs2_holder_uninit(&gh);
+ if (rw == READ)
+ mutex_unlock(&inode->i_mutex);
return rv;
}
/**
- * gfs2_direct_IO
- *
- * This is called with a shared lock already held for the read path.
- * Currently, no locks are held when the write path is called.
- */
-static ssize_t gfs2_direct_IO(int rw, struct kiocb *iocb,
- const struct iovec *iov, loff_t offset,
- unsigned long nr_segs)
-{
- struct file *file = iocb->ki_filp;
- struct inode *inode = file->f_mapping->host;
- struct gfs2_inode *ip = GFS2_I(inode);
- struct gfs2_sbd *sdp = GFS2_SB(inode);
- int ret;
-
- if (rw == WRITE)
- return gfs2_direct_IO_write(iocb, iov, offset, nr_segs);
-
- if (gfs2_assert_warn(sdp, gfs2_glock_is_locked_by_me(ip->i_gl)) ||
- gfs2_assert_warn(sdp, !gfs2_is_stuffed(ip)))
- return -EINVAL;
-
- mutex_lock(&inode->i_mutex);
- ret = __blockdev_direct_IO(READ, iocb, inode, inode->i_sb->s_bdev, iov,
- offset, nr_segs, gfs2_get_block, NULL,
- DIO_OWN_LOCKING);
- mutex_unlock(&inode->i_mutex);
- return ret;
-}
-
-/**
* stuck_releasepage - We're stuck in gfs2_releasepage(). Print stuff out.
* @bh: the buffer we're stuck on
*
@@ -765,7 +743,7 @@
}
while (bh != head);
- out:
+out:
return try_to_free_buffers(page);
}
diff --git a/fs/gfs2/ops_file.c b/fs/gfs2/ops_file.c
index 6764ca6..d13e04e 100644
--- a/fs/gfs2/ops_file.c
+++ b/fs/gfs2/ops_file.c
@@ -148,170 +148,6 @@
return error;
}
-
-static ssize_t gfs2_direct_IO_read(struct kiocb *iocb, const struct iovec *iov,
- loff_t offset, unsigned long nr_segs)
-{
- struct file *file = iocb->ki_filp;
- struct address_space *mapping = file->f_mapping;
- ssize_t retval;
-
- retval = filemap_write_and_wait(mapping);
- if (retval == 0) {
- retval = mapping->a_ops->direct_IO(READ, iocb, iov, offset,
- nr_segs);
- }
- return retval;
-}
-
-/**
- * __gfs2_file_aio_read - The main GFS2 read function
- *
- * N.B. This is almost, but not quite the same as __generic_file_aio_read()
- * the important subtle different being that inode->i_size isn't valid
- * unless we are holding a lock, and we do this _only_ on the O_DIRECT
- * path since otherwise locking is done entirely at the page cache
- * layer.
- */
-static ssize_t __gfs2_file_aio_read(struct kiocb *iocb,
- const struct iovec *iov,
- unsigned long nr_segs, loff_t *ppos)
-{
- struct file *filp = iocb->ki_filp;
- struct gfs2_inode *ip = GFS2_I(filp->f_mapping->host);
- struct gfs2_holder gh;
- ssize_t retval;
- unsigned long seg;
- size_t count;
-
- count = 0;
- for (seg = 0; seg < nr_segs; seg++) {
- const struct iovec *iv = &iov[seg];
-
- /*
- * If any segment has a negative length, or the cumulative
- * length ever wraps negative then return -EINVAL.
- */
- count += iv->iov_len;
- if (unlikely((ssize_t)(count|iv->iov_len) < 0))
- return -EINVAL;
- if (access_ok(VERIFY_WRITE, iv->iov_base, iv->iov_len))
- continue;
- if (seg == 0)
- return -EFAULT;
- nr_segs = seg;
- count -= iv->iov_len; /* This segment is no good */
- break;
- }
-
- /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
- if (filp->f_flags & O_DIRECT) {
- loff_t pos = *ppos, size;
- struct address_space *mapping;
- struct inode *inode;
-
- mapping = filp->f_mapping;
- inode = mapping->host;
- retval = 0;
- if (!count)
- goto out; /* skip atime */
-
- gfs2_holder_init(ip->i_gl, LM_ST_SHARED, GL_ATIME, &gh);
- retval = gfs2_glock_nq_m_atime(1, &gh);
- if (retval)
- goto out;
- if (gfs2_is_stuffed(ip)) {
- gfs2_glock_dq_m(1, &gh);
- gfs2_holder_uninit(&gh);
- goto fallback_to_normal;
- }
- size = i_size_read(inode);
- if (pos < size) {
- retval = gfs2_direct_IO_read(iocb, iov, pos, nr_segs);
- if (retval > 0 && !is_sync_kiocb(iocb))
- retval = -EIOCBQUEUED;
- if (retval > 0)
- *ppos = pos + retval;
- }
- file_accessed(filp);
- gfs2_glock_dq_m(1, &gh);
- gfs2_holder_uninit(&gh);
- goto out;
- }
-
-fallback_to_normal:
- retval = 0;
- if (count) {
- for (seg = 0; seg < nr_segs; seg++) {
- read_descriptor_t desc;
-
- desc.written = 0;
- desc.arg.buf = iov[seg].iov_base;
- desc.count = iov[seg].iov_len;
- if (desc.count == 0)
- continue;
- desc.error = 0;
- do_generic_file_read(filp,ppos,&desc,file_read_actor);
- retval += desc.written;
- if (desc.error) {
- retval = retval ?: desc.error;
- break;
- }
- }
- }
-out:
- return retval;
-}
-
-/**
- * gfs2_read - Read bytes from a file
- * @file: The file to read from
- * @buf: The buffer to copy into
- * @size: The amount of data requested
- * @offset: The current file offset
- *
- * Outputs: Offset - updated according to number of bytes read
- *
- * Returns: The number of bytes read, errno on failure
- */
-
-static ssize_t gfs2_read(struct file *filp, char __user *buf, size_t size,
- loff_t *offset)
-{
- struct iovec local_iov = { .iov_base = buf, .iov_len = size };
- struct kiocb kiocb;
- ssize_t ret;
-
- init_sync_kiocb(&kiocb, filp);
- ret = __gfs2_file_aio_read(&kiocb, &local_iov, 1, offset);
- if (-EIOCBQUEUED == ret)
- ret = wait_on_sync_kiocb(&kiocb);
- return ret;
-}
-
-static ssize_t gfs2_file_readv(struct file *filp, const struct iovec *iov,
- unsigned long nr_segs, loff_t *ppos)
-{
- struct kiocb kiocb;
- ssize_t ret;
-
- init_sync_kiocb(&kiocb, filp);
- ret = __gfs2_file_aio_read(&kiocb, iov, nr_segs, ppos);
- if (-EIOCBQUEUED == ret)
- ret = wait_on_sync_kiocb(&kiocb);
- return ret;
-}
-
-static ssize_t gfs2_file_aio_read(struct kiocb *iocb, char __user *buf,
- size_t count, loff_t pos)
-{
- struct iovec local_iov = { .iov_base = buf, .iov_len = count };
-
- BUG_ON(iocb->ki_pos != pos);
- return __gfs2_file_aio_read(iocb, &local_iov, 1, &iocb->ki_pos);
-}
-
-
/**
* filldir_reg_func - Report a directory entry to the caller of gfs2_dir_read()
* @opaque: opaque data used by the function
@@ -949,9 +785,9 @@
const struct file_operations gfs2_file_fops = {
.llseek = gfs2_llseek,
- .read = gfs2_read,
- .readv = gfs2_file_readv,
- .aio_read = gfs2_file_aio_read,
+ .read = generic_file_read,
+ .readv = generic_file_readv,
+ .aio_read = generic_file_aio_read,
.write = generic_file_write,
.writev = generic_file_writev,
.aio_write = generic_file_aio_write,
