[RFC PATCH 73/76] afs: Add O_DIRECT read support

From: David Howells
Date: Fri Nov 20 2020 - 10:20:23 EST

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Add synchronous O_DIRECT read support to AFS (no AIO yet). It can
theoretically handle reads up to the maximum size describable by loff_t -
and given an iterator with sufficiently capacity to handle that and given
support on the server.

Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
---

fs/afs/file.c | 59 +++++++++++++++++++++++++++++++++++
fs/afs/fsclient.c | 18 ++++++++---
fs/afs/internal.h | 2 +
fs/afs/write.c | 88 +++++++++++++++++++++++++++++++++++++++++++++++-----
fs/afs/yfsclient.c | 12 +++++--
5 files changed, 161 insertions(+), 18 deletions(-)

diff --git a/fs/afs/file.c b/fs/afs/file.c
index bd070684de53..27445866531c 100644
--- a/fs/afs/file.c
+++ b/fs/afs/file.c
@@ -24,6 +24,7 @@ static void afs_invalidatepage(struct page *page, unsigned int offset,
static int afs_releasepage(struct page *page, gfp_t gfp_flags);

static void afs_readahead(struct readahead_control *ractl);
+static ssize_t afs_direct_IO(struct kiocb *iocb, struct iov_iter *iter);

const struct file_operations afs_file_operations = {
.open = afs_open,
@@ -53,6 +54,7 @@ const struct address_space_operations afs_fs_aops = {
.launder_page = afs_launder_page,
.releasepage = afs_releasepage,
.invalidatepage = afs_invalidatepage,
+ .direct_IO = afs_direct_IO,
.write_begin = afs_write_begin,
.write_end = afs_write_end,
.writepage = afs_writepage,
@@ -529,3 +531,60 @@ static int afs_file_mmap(struct file *file, struct vm_area_struct *vma)
vma->vm_ops = &afs_vm_ops;
return ret;
}
+
+/*
+ * Direct file read operation for an AFS file.
+ *
+ * TODO: To support AIO, the pages in the iterator have to be copied and
+ * refs taken on them. Then -EIOCBQUEUED needs to be returned.
+ * iocb->ki_complete must then be called upon completion of the operation.
+ */
+static ssize_t afs_file_direct_read(struct kiocb *iocb, struct iov_iter *iter)
+{
+ struct file *file = iocb->ki_filp;
+ struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
+ struct afs_read *req;
+ ssize_t ret, transferred;
+
+ _enter("%llx,%zx", iocb->ki_pos, iov_iter_count(iter));
+
+ req = afs_alloc_read(GFP_KERNEL);
+ if (!req)
+ return -ENOMEM;
+
+ req->vnode = vnode;
+ req->key = key_get(afs_file_key(file));
+ req->pos = iocb->ki_pos;
+ req->len = iov_iter_count(iter);
+ req->iter = iter;
+
+ task_io_account_read(req->len);
+
+ // TODO nfs_start_io_direct(inode);
+ ret = afs_fetch_data(vnode, req);
+ if (ret == 0)
+ transferred = req->actual_len;
+ afs_put_read(req);
+
+ // TODO nfs_end_io_direct(inode);
+
+ if (ret == 0)
+ ret = transferred;
+
+ BUG_ON(ret == -EIOCBQUEUED); // TODO
+ //if (iocb->ki_complete)
+ // iocb->ki_complete(iocb, ret, 0); // only if ret == -EIOCBQUEUED
+
+ _leave(" = %zu", ret);
+ return ret;
+}
+
+/*
+ * Do direct I/O.
+ */
+static ssize_t afs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
+{
+ if (iov_iter_rw(iter) == READ)
+ return afs_file_direct_read(iocb, iter);
+ return afs_file_direct_write(iocb, iter);
+}
diff --git a/fs/afs/fsclient.c b/fs/afs/fsclient.c
index 2f695a260442..5e42af4d1ded 100644
--- a/fs/afs/fsclient.c
+++ b/fs/afs/fsclient.c
@@ -438,7 +438,7 @@ static void afs_fs_fetch_data64(struct afs_operation *op)
bp[3] = htonl(vp->fid.unique);
bp[4] = htonl(upper_32_bits(req->pos));
bp[5] = htonl(lower_32_bits(req->pos));
- bp[6] = 0;
+ bp[6] = htonl(upper_32_bits(req->len));
bp[7] = htonl(lower_32_bits(req->len));

trace_afs_make_fs_call(call, &vp->fid);
@@ -1058,6 +1058,7 @@ static void afs_fs_store_data64(struct afs_operation *op)
struct afs_vnode_param *vp = &op->file[0];
struct afs_call *call;
__be32 *bp;
+ u32 mask = 0;

_enter(",%x,{%llx:%llu},,",
key_serial(op->key), vp->fid.vid, vp->fid.vnode);
@@ -1070,6 +1071,9 @@ static void afs_fs_store_data64(struct afs_operation *op)

call->write_iter = op->store.write_iter;

+ if (op->flags & AFS_OPERATION_SET_MTIME)
+ mask |= AFS_SET_MTIME;
+
/* marshall the parameters */
bp = call->request;
*bp++ = htonl(FSSTOREDATA64);
@@ -1077,8 +1081,8 @@ static void afs_fs_store_data64(struct afs_operation *op)
*bp++ = htonl(vp->fid.vnode);
*bp++ = htonl(vp->fid.unique);

- *bp++ = htonl(AFS_SET_MTIME); /* mask */
- *bp++ = htonl(op->mtime.tv_sec); /* mtime */
+ *bp++ = htonl(mask);
+ *bp++ = htonl(op->mtime.tv_sec);
*bp++ = 0; /* owner */
*bp++ = 0; /* group */
*bp++ = 0; /* unix mode */
@@ -1103,6 +1107,7 @@ void afs_fs_store_data(struct afs_operation *op)
struct afs_vnode_param *vp = &op->file[0];
struct afs_call *call;
__be32 *bp;
+ u32 mask = 0;

_enter(",%x,{%llx:%llu},,",
key_serial(op->key), vp->fid.vid, vp->fid.vnode);
@@ -1125,6 +1130,9 @@ void afs_fs_store_data(struct afs_operation *op)

call->write_iter = op->store.write_iter;

+ if (op->flags & AFS_OPERATION_SET_MTIME)
+ mask |= AFS_SET_MTIME;
+
/* marshall the parameters */
bp = call->request;
*bp++ = htonl(FSSTOREDATA);
@@ -1132,8 +1140,8 @@ void afs_fs_store_data(struct afs_operation *op)
*bp++ = htonl(vp->fid.vnode);
*bp++ = htonl(vp->fid.unique);

- *bp++ = htonl(AFS_SET_MTIME); /* mask */
- *bp++ = htonl(op->mtime.tv_sec); /* mtime */
+ *bp++ = htonl(mask);
+ *bp++ = htonl(op->mtime.tv_sec);
*bp++ = 0; /* owner */
*bp++ = 0; /* group */
*bp++ = 0; /* unix mode */
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index bc76c08b9f38..e80fb6fe15b3 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -853,6 +853,7 @@ struct afs_operation {
#define AFS_OPERATION_TRIED_ALL 0x0400 /* Set if we've tried all the fileservers */
#define AFS_OPERATION_RETRY_SERVER 0x0800 /* Set if we should retry the current server */
#define AFS_OPERATION_DIR_CONFLICT 0x1000 /* Set if we detected a 3rd-party dir change */
+#define AFS_OPERATION_SET_MTIME 0x2000 /* Set if we should try to store the mtime */
};

/*
@@ -1506,6 +1507,7 @@ extern int afs_fsync(struct file *, loff_t, loff_t, int);
extern vm_fault_t afs_page_mkwrite(struct vm_fault *vmf);
extern void afs_prune_wb_keys(struct afs_vnode *);
extern int afs_launder_page(struct page *);
+extern ssize_t afs_file_direct_write(struct kiocb *, struct iov_iter *);

/*
* xattr.c
diff --git a/fs/afs/write.c b/fs/afs/write.c
index 627b08d8de1f..bab110c00abd 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -387,7 +387,7 @@ static int afs_store_data(struct afs_vnode *vnode, struct iov_iter *iter, loff_t
op->store.i_size = max(pos + size, i_size);
op->store.laundering = laundering;
op->mtime = vnode->vfs_inode.i_mtime;
- op->flags |= AFS_OPERATION_UNINTR;
+ op->flags |= AFS_OPERATION_SET_MTIME | AFS_OPERATION_UNINTR;
op->ops = &afs_store_data_operation;

try_next_key:
@@ -810,7 +810,6 @@ int afs_writepages(struct address_space *mapping,
ssize_t afs_file_write(struct kiocb *iocb, struct iov_iter *from)
{
struct afs_vnode *vnode = AFS_FS_I(file_inode(iocb->ki_filp));
- ssize_t result;
size_t count = iov_iter_count(from);

_enter("{%llx:%llu},{%zu},",
@@ -822,13 +821,7 @@ ssize_t afs_file_write(struct kiocb *iocb, struct iov_iter *from)
return -EBUSY;
}

- if (!count)
- return 0;
-
- result = generic_file_write_iter(iocb, from);
-
- _leave(" = %zd", result);
- return result;
+ return generic_file_write_iter(iocb, from);
}

/*
@@ -997,3 +990,80 @@ static void afs_write_to_cache(struct afs_vnode *vnode,
vnode->vfs_inode.i_mapping, start, len, i_size,
afs_write_to_cache_done, vnode);
}
+
+static void afs_dio_store_data_success(struct afs_operation *op)
+{
+ struct afs_vnode *vnode = op->file[0].vnode;
+
+ op->ctime = op->file[0].scb.status.mtime_client;
+ afs_vnode_commit_status(op, &op->file[0]);
+ if (op->error == 0) {
+ afs_stat_v(vnode, n_stores);
+ atomic_long_add(op->store.size, &afs_v2net(vnode)->n_store_bytes);
+ }
+}
+
+static const struct afs_operation_ops afs_dio_store_data_operation = {
+ .issue_afs_rpc = afs_fs_store_data,
+ .issue_yfs_rpc = yfs_fs_store_data,
+ .success = afs_dio_store_data_success,
+};
+
+/*
+ * Direct file write operation for an AFS file.
+ *
+ * TODO: To support AIO, the pages in the iterator have to be copied and
+ * refs taken on them. Then -EIOCBQUEUED needs to be returned.
+ * iocb->ki_complete must then be called upon completion of the operation.
+ */
+ssize_t afs_file_direct_write(struct kiocb *iocb, struct iov_iter *iter)
+{
+ struct file *file = iocb->ki_filp;
+ struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
+ struct afs_operation *op;
+ loff_t size = iov_iter_count(iter), i_size;
+ ssize_t ret;
+
+ _enter("%s{%llx:%llu.%u},%llx,%llx",
+ vnode->volume->name,
+ vnode->fid.vid,
+ vnode->fid.vnode,
+ vnode->fid.unique,
+ size, iocb->ki_pos);
+
+ op = afs_alloc_operation(afs_file_key(file), vnode->volume);
+ if (IS_ERR(op))
+ return -ENOMEM;
+
+ i_size = i_size_read(&vnode->vfs_inode);
+
+ afs_op_set_vnode(op, 0, vnode);
+ op->file[0].dv_delta = 1;
+ op->file[0].set_size = true;
+ op->store.write_iter = iter;
+ op->store.pos = iocb->ki_pos;
+ op->store.size = size;
+ op->store.i_size = max(iocb->ki_pos + size, i_size);
+ op->ops = &afs_dio_store_data_operation;
+
+ //if (!is_sync_kiocb(iocb)) {
+
+ ret = afs_do_sync_operation(op);
+ if (ret == 0)
+ ret = size;
+
+ {
+ struct afs_vnode_cache_aux aux = {
+ .data_version = vnode->status.data_version,
+ };
+ fscache_invalidate(afs_vnode_cache(vnode), &aux,
+ i_size_read(&vnode->vfs_inode),
+ FSCACHE_INVAL_DIO_WRITE);
+ }
+
+ //if (iocb->ki_complete)
+ // iocb->ki_complete(iocb, ret, 0); // only if ret == -EIOCBQUEUED
+
+ _leave(" = %zd", ret);
+ return ret;
+}
diff --git a/fs/afs/yfsclient.c b/fs/afs/yfsclient.c
index 2b35cba8ad62..a8c4e230002d 100644
--- a/fs/afs/yfsclient.c
+++ b/fs/afs/yfsclient.c
@@ -95,12 +95,16 @@ static __be32 *xdr_encode_YFSStoreStatus_mode(__be32 *bp, mode_t mode)
return bp + xdr_size(x);
}

-static __be32 *xdr_encode_YFSStoreStatus_mtime(__be32 *bp, const struct timespec64 *t)
+static __be32 *xdr_encode_YFSStoreStatus_mtime(__be32 *bp, struct afs_operation *op)
{
struct yfs_xdr_YFSStoreStatus *x = (void *)bp;
- s64 mtime = linux_to_yfs_time(t);
+ s64 mtime = linux_to_yfs_time(&op->mtime);
+ u32 mask = 0;

- x->mask = htonl(AFS_SET_MTIME);
+ if (op->flags & AFS_OPERATION_SET_MTIME)
+ mask |= AFS_SET_MTIME;
+
+ x->mask = htonl(mask);
x->mode = htonl(0);
x->mtime_client = u64_to_xdr(mtime);
x->owner = u64_to_xdr(0);
@@ -1103,7 +1107,7 @@ void yfs_fs_store_data(struct afs_operation *op)
bp = xdr_encode_u32(bp, YFSSTOREDATA64);
bp = xdr_encode_u32(bp, 0); /* RPC flags */
bp = xdr_encode_YFSFid(bp, &vp->fid);
- bp = xdr_encode_YFSStoreStatus_mtime(bp, &op->mtime);
+ bp = xdr_encode_YFSStoreStatus_mtime(bp, op);
bp = xdr_encode_u64(bp, op->store.pos);
bp = xdr_encode_u64(bp, op->store.size);
bp = xdr_encode_u64(bp, op->store.i_size);

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