Initial import

1 files changed, 1344 insertions, 0 deletions

diff --git a/fs/ceph/file.c b/fs/ceph/file.c
new file mode 100644
index 000000000..3b6b522b4
--- /dev/null
+++ b/fs/ceph/file.c
@@ -0,0 +1,1344 @@
+#include <linux/ceph/ceph_debug.h>
+
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/file.h>
+#include <linux/mount.h>
+#include <linux/namei.h>
+#include <linux/writeback.h>
+#include <linux/falloc.h>
+
+#include "super.h"
+#include "mds_client.h"
+#include "cache.h"
+
+/*
+ * Ceph file operations
+ *
+ * Implement basic open/close functionality, and implement
+ * read/write.
+ *
+ * We implement three modes of file I/O:
+ *  - buffered uses the generic_file_aio_{read,write} helpers
+ *
+ *  - synchronous is used when there is multi-client read/write
+ *    sharing, avoids the page cache, and synchronously waits for an
+ *    ack from the OSD.
+ *
+ *  - direct io takes the variant of the sync path that references
+ *    user pages directly.
+ *
+ * fsync() flushes and waits on dirty pages, but just queues metadata
+ * for writeback: since the MDS can recover size and mtime there is no
+ * need to wait for MDS acknowledgement.
+ */
+
+
+/*
+ * Prepare an open request.  Preallocate ceph_cap to avoid an
+ * inopportune ENOMEM later.
+ */
+static struct ceph_mds_request *
+prepare_open_request(struct super_block *sb, int flags, int create_mode)
+{
+	struct ceph_fs_client *fsc = ceph_sb_to_client(sb);
+	struct ceph_mds_client *mdsc = fsc->mdsc;
+	struct ceph_mds_request *req;
+	int want_auth = USE_ANY_MDS;
+	int op = (flags & O_CREAT) ? CEPH_MDS_OP_CREATE : CEPH_MDS_OP_OPEN;
+
+	if (flags & (O_WRONLY|O_RDWR|O_CREAT|O_TRUNC))
+		want_auth = USE_AUTH_MDS;
+
+	req = ceph_mdsc_create_request(mdsc, op, want_auth);
+	if (IS_ERR(req))
+		goto out;
+	req->r_fmode = ceph_flags_to_mode(flags);
+	req->r_args.open.flags = cpu_to_le32(flags);
+	req->r_args.open.mode = cpu_to_le32(create_mode);
+out:
+	return req;
+}
+
+/*
+ * initialize private struct file data.
+ * if we fail, clean up by dropping fmode reference on the ceph_inode
+ */
+static int ceph_init_file(struct inode *inode, struct file *file, int fmode)
+{
+	struct ceph_file_info *cf;
+	int ret = 0;
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	struct ceph_fs_client *fsc = ceph_sb_to_client(inode->i_sb);
+	struct ceph_mds_client *mdsc = fsc->mdsc;
+
+	switch (inode->i_mode & S_IFMT) {
+	case S_IFREG:
+		/* First file open request creates the cookie, we want to keep
+		 * this cookie around for the filetime of the inode as not to
+		 * have to worry about fscache register / revoke / operation
+		 * races.
+		 *
+		 * Also, if we know the operation is going to invalidate data
+		 * (non readonly) just nuke the cache right away.
+		 */
+		ceph_fscache_register_inode_cookie(mdsc->fsc, ci);
+		if ((fmode & CEPH_FILE_MODE_WR))
+			ceph_fscache_invalidate(inode);
+	case S_IFDIR:
+		dout("init_file %p %p 0%o (regular)\n", inode, file,
+		     inode->i_mode);
+		cf = kmem_cache_alloc(ceph_file_cachep, GFP_NOFS | __GFP_ZERO);
+		if (cf == NULL) {
+			ceph_put_fmode(ceph_inode(inode), fmode); /* clean up */
+			return -ENOMEM;
+		}
+		cf->fmode = fmode;
+		cf->next_offset = 2;
+		file->private_data = cf;
+		BUG_ON(inode->i_fop->release != ceph_release);
+		break;
+
+	case S_IFLNK:
+		dout("init_file %p %p 0%o (symlink)\n", inode, file,
+		     inode->i_mode);
+		ceph_put_fmode(ceph_inode(inode), fmode); /* clean up */
+		break;
+
+	default:
+		dout("init_file %p %p 0%o (special)\n", inode, file,
+		     inode->i_mode);
+		/*
+		 * we need to drop the open ref now, since we don't
+		 * have .release set to ceph_release.
+		 */
+		ceph_put_fmode(ceph_inode(inode), fmode); /* clean up */
+		BUG_ON(inode->i_fop->release == ceph_release);
+
+		/* call the proper open fop */
+		ret = inode->i_fop->open(inode, file);
+	}
+	return ret;
+}
+
+/*
+ * If we already have the requisite capabilities, we can satisfy
+ * the open request locally (no need to request new caps from the
+ * MDS).  We do, however, need to inform the MDS (asynchronously)
+ * if our wanted caps set expands.
+ */
+int ceph_open(struct inode *inode, struct file *file)
+{
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	struct ceph_fs_client *fsc = ceph_sb_to_client(inode->i_sb);
+	struct ceph_mds_client *mdsc = fsc->mdsc;
+	struct ceph_mds_request *req;
+	struct ceph_file_info *cf = file->private_data;
+	struct inode *parent_inode = NULL;
+	int err;
+	int flags, fmode, wanted;
+
+	if (cf) {
+		dout("open file %p is already opened\n", file);
+		return 0;
+	}
+
+	/* filter out O_CREAT|O_EXCL; vfs did that already.  yuck. */
+	flags = file->f_flags & ~(O_CREAT|O_EXCL);
+	if (S_ISDIR(inode->i_mode))
+		flags = O_DIRECTORY;  /* mds likes to know */
+
+	dout("open inode %p ino %llx.%llx file %p flags %d (%d)\n", inode,
+	     ceph_vinop(inode), file, flags, file->f_flags);
+	fmode = ceph_flags_to_mode(flags);
+	wanted = ceph_caps_for_mode(fmode);
+
+	/* snapped files are read-only */
+	if (ceph_snap(inode) != CEPH_NOSNAP && (file->f_mode & FMODE_WRITE))
+		return -EROFS;
+
+	/* trivially open snapdir */
+	if (ceph_snap(inode) == CEPH_SNAPDIR) {
+		spin_lock(&ci->i_ceph_lock);
+		__ceph_get_fmode(ci, fmode);
+		spin_unlock(&ci->i_ceph_lock);
+		return ceph_init_file(inode, file, fmode);
+	}
+
+	/*
+	 * No need to block if we have caps on the auth MDS (for
+	 * write) or any MDS (for read).  Update wanted set
+	 * asynchronously.
+	 */
+	spin_lock(&ci->i_ceph_lock);
+	if (__ceph_is_any_real_caps(ci) &&
+	    (((fmode & CEPH_FILE_MODE_WR) == 0) || ci->i_auth_cap)) {
+		int mds_wanted = __ceph_caps_mds_wanted(ci);
+		int issued = __ceph_caps_issued(ci, NULL);
+
+		dout("open %p fmode %d want %s issued %s using existing\n",
+		     inode, fmode, ceph_cap_string(wanted),
+		     ceph_cap_string(issued));
+		__ceph_get_fmode(ci, fmode);
+		spin_unlock(&ci->i_ceph_lock);
+
+		/* adjust wanted? */
+		if ((issued & wanted) != wanted &&
+		    (mds_wanted & wanted) != wanted &&
+		    ceph_snap(inode) != CEPH_SNAPDIR)
+			ceph_check_caps(ci, 0, NULL);
+
+		return ceph_init_file(inode, file, fmode);
+	} else if (ceph_snap(inode) != CEPH_NOSNAP &&
+		   (ci->i_snap_caps & wanted) == wanted) {
+		__ceph_get_fmode(ci, fmode);
+		spin_unlock(&ci->i_ceph_lock);
+		return ceph_init_file(inode, file, fmode);
+	}
+
+	spin_unlock(&ci->i_ceph_lock);
+
+	dout("open fmode %d wants %s\n", fmode, ceph_cap_string(wanted));
+	req = prepare_open_request(inode->i_sb, flags, 0);
+	if (IS_ERR(req)) {
+		err = PTR_ERR(req);
+		goto out;
+	}
+	req->r_inode = inode;
+	ihold(inode);
+
+	req->r_num_caps = 1;
+	if (flags & O_CREAT)
+		parent_inode = ceph_get_dentry_parent_inode(file->f_path.dentry);
+	err = ceph_mdsc_do_request(mdsc, parent_inode, req);
+	iput(parent_inode);
+	if (!err)
+		err = ceph_init_file(inode, file, req->r_fmode);
+	ceph_mdsc_put_request(req);
+	dout("open result=%d on %llx.%llx\n", err, ceph_vinop(inode));
+out:
+	return err;
+}
+
+
+/*
+ * Do a lookup + open with a single request.  If we get a non-existent
+ * file or symlink, return 1 so the VFS can retry.
+ */
+int ceph_atomic_open(struct inode *dir, struct dentry *dentry,
+		     struct file *file, unsigned flags, umode_t mode,
+		     int *opened)
+{
+	struct ceph_fs_client *fsc = ceph_sb_to_client(dir->i_sb);
+	struct ceph_mds_client *mdsc = fsc->mdsc;
+	struct ceph_mds_request *req;
+	struct dentry *dn;
+	struct ceph_acls_info acls = {};
+	int err;
+
+	dout("atomic_open %p dentry %p '%pd' %s flags %d mode 0%o\n",
+	     dir, dentry, dentry,
+	     d_unhashed(dentry) ? "unhashed" : "hashed", flags, mode);
+
+	if (dentry->d_name.len > NAME_MAX)
+		return -ENAMETOOLONG;
+
+	err = ceph_init_dentry(dentry);
+	if (err < 0)
+		return err;
+
+	if (flags & O_CREAT) {
+		err = ceph_pre_init_acls(dir, &mode, &acls);
+		if (err < 0)
+			return err;
+	}
+
+	/* do the open */
+	req = prepare_open_request(dir->i_sb, flags, mode);
+	if (IS_ERR(req)) {
+		err = PTR_ERR(req);
+		goto out_acl;
+	}
+	req->r_dentry = dget(dentry);
+	req->r_num_caps = 2;
+	if (flags & O_CREAT) {
+		req->r_dentry_drop = CEPH_CAP_FILE_SHARED;
+		req->r_dentry_unless = CEPH_CAP_FILE_EXCL;
+		if (acls.pagelist) {
+			req->r_pagelist = acls.pagelist;
+			acls.pagelist = NULL;
+		}
+	}
+	req->r_locked_dir = dir;           /* caller holds dir->i_mutex */
+	err = ceph_mdsc_do_request(mdsc,
+				   (flags & (O_CREAT|O_TRUNC)) ? dir : NULL,
+				   req);
+	err = ceph_handle_snapdir(req, dentry, err);
+	if (err)
+		goto out_req;
+
+	if (err == 0 && (flags & O_CREAT) && !req->r_reply_info.head->is_dentry)
+		err = ceph_handle_notrace_create(dir, dentry);
+
+	if (d_unhashed(dentry)) {
+		dn = ceph_finish_lookup(req, dentry, err);
+		if (IS_ERR(dn))
+			err = PTR_ERR(dn);
+	} else {
+		/* we were given a hashed negative dentry */
+		dn = NULL;
+	}
+	if (err)
+		goto out_req;
+	if (dn || d_really_is_negative(dentry) || d_is_symlink(dentry)) {
+		/* make vfs retry on splice, ENOENT, or symlink */
+		dout("atomic_open finish_no_open on dn %p\n", dn);
+		err = finish_no_open(file, dn);
+	} else {
+		dout("atomic_open finish_open on dn %p\n", dn);
+		if (req->r_op == CEPH_MDS_OP_CREATE && req->r_reply_info.has_create_ino) {
+			ceph_init_inode_acls(d_inode(dentry), &acls);
+			*opened |= FILE_CREATED;
+		}
+		err = finish_open(file, dentry, ceph_open, opened);
+	}
+out_req:
+	if (!req->r_err && req->r_target_inode)
+		ceph_put_fmode(ceph_inode(req->r_target_inode), req->r_fmode);
+	ceph_mdsc_put_request(req);
+out_acl:
+	ceph_release_acls_info(&acls);
+	dout("atomic_open result=%d\n", err);
+	return err;
+}
+
+int ceph_release(struct inode *inode, struct file *file)
+{
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	struct ceph_file_info *cf = file->private_data;
+
+	dout("release inode %p file %p\n", inode, file);
+	ceph_put_fmode(ci, cf->fmode);
+	if (cf->last_readdir)
+		ceph_mdsc_put_request(cf->last_readdir);
+	kfree(cf->last_name);
+	kfree(cf->dir_info);
+	dput(cf->dentry);
+	kmem_cache_free(ceph_file_cachep, cf);
+
+	/* wake up anyone waiting for caps on this inode */
+	wake_up_all(&ci->i_cap_wq);
+	return 0;
+}
+
+enum {
+	CHECK_EOF = 1,
+	READ_INLINE = 2,
+};
+
+/*
+ * Read a range of bytes striped over one or more objects.  Iterate over
+ * objects we stripe over.  (That's not atomic, but good enough for now.)
+ *
+ * If we get a short result from the OSD, check against i_size; we need to
+ * only return a short read to the caller if we hit EOF.
+ */
+static int striped_read(struct inode *inode,
+			u64 off, u64 len,
+			struct page **pages, int num_pages,
+			int *checkeof, bool o_direct,
+			unsigned long buf_align)
+{
+	struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	u64 pos, this_len, left;
+	int io_align, page_align;
+	int pages_left;
+	int read;
+	struct page **page_pos;
+	int ret;
+	bool hit_stripe, was_short;
+
+	/*
+	 * we may need to do multiple reads.  not atomic, unfortunately.
+	 */
+	pos = off;
+	left = len;
+	page_pos = pages;
+	pages_left = num_pages;
+	read = 0;
+	io_align = off & ~PAGE_MASK;
+
+more:
+	if (o_direct)
+		page_align = (pos - io_align + buf_align) & ~PAGE_MASK;
+	else
+		page_align = pos & ~PAGE_MASK;
+	this_len = left;
+	ret = ceph_osdc_readpages(&fsc->client->osdc, ceph_vino(inode),
+				  &ci->i_layout, pos, &this_len,
+				  ci->i_truncate_seq,
+				  ci->i_truncate_size,
+				  page_pos, pages_left, page_align);
+	if (ret == -ENOENT)
+		ret = 0;
+	hit_stripe = this_len < left;
+	was_short = ret >= 0 && ret < this_len;
+	dout("striped_read %llu~%llu (read %u) got %d%s%s\n", pos, left, read,
+	     ret, hit_stripe ? " HITSTRIPE" : "", was_short ? " SHORT" : "");
+
+	if (ret >= 0) {
+		int didpages;
+		if (was_short && (pos + ret < inode->i_size)) {
+			int zlen = min(this_len - ret,
+				       inode->i_size - pos - ret);
+			int zoff = (o_direct ? buf_align : io_align) +
+				    read + ret;
+			dout(" zero gap %llu to %llu\n",
+				pos + ret, pos + ret + zlen);
+			ceph_zero_page_vector_range(zoff, zlen, pages);
+			ret += zlen;
+		}
+
+		didpages = (page_align + ret) >> PAGE_CACHE_SHIFT;
+		pos += ret;
+		read = pos - off;
+		left -= ret;
+		page_pos += didpages;
+		pages_left -= didpages;
+
+		/* hit stripe and need continue*/
+		if (left && hit_stripe && pos < inode->i_size)
+			goto more;
+	}
+
+	if (read > 0) {
+		ret = read;
+		/* did we bounce off eof? */
+		if (pos + left > inode->i_size)
+			*checkeof = CHECK_EOF;
+	}
+
+	dout("striped_read returns %d\n", ret);
+	return ret;
+}
+
+/*
+ * Completely synchronous read and write methods.  Direct from __user
+ * buffer to osd, or directly to user pages (if O_DIRECT).
+ *
+ * If the read spans object boundary, just do multiple reads.
+ */
+static ssize_t ceph_sync_read(struct kiocb *iocb, struct iov_iter *i,
+				int *checkeof)
+{
+	struct file *file = iocb->ki_filp;
+	struct inode *inode = file_inode(file);
+	struct page **pages;
+	u64 off = iocb->ki_pos;
+	int num_pages, ret;
+	size_t len = iov_iter_count(i);
+
+	dout("sync_read on file %p %llu~%u %s\n", file, off,
+	     (unsigned)len,
+	     (file->f_flags & O_DIRECT) ? "O_DIRECT" : "");
+
+	if (!len)
+		return 0;
+	/*
+	 * flush any page cache pages in this range.  this
+	 * will make concurrent normal and sync io slow,
+	 * but it will at least behave sensibly when they are
+	 * in sequence.
+	 */
+	ret = filemap_write_and_wait_range(inode->i_mapping, off,
+						off + len);
+	if (ret < 0)
+		return ret;
+
+	if (iocb->ki_flags & IOCB_DIRECT) {
+		while (iov_iter_count(i)) {
+			size_t start;
+			ssize_t n;
+
+			n = iov_iter_get_pages_alloc(i, &pages, INT_MAX, &start);
+			if (n < 0)
+				return n;
+
+			num_pages = (n + start + PAGE_SIZE - 1) / PAGE_SIZE;
+
+			ret = striped_read(inode, off, n,
+					   pages, num_pages, checkeof,
+					   1, start);
+
+			ceph_put_page_vector(pages, num_pages, true);
+
+			if (ret <= 0)
+				break;
+			off += ret;
+			iov_iter_advance(i, ret);
+			if (ret < n)
+				break;
+		}
+	} else {
+		num_pages = calc_pages_for(off, len);
+		pages = ceph_alloc_page_vector(num_pages, GFP_NOFS);
+		if (IS_ERR(pages))
+			return PTR_ERR(pages);
+		ret = striped_read(inode, off, len, pages,
+					num_pages, checkeof, 0, 0);
+		if (ret > 0) {
+			int l, k = 0;
+			size_t left = ret;
+
+			while (left) {
+				size_t page_off = off & ~PAGE_MASK;
+				size_t copy = min_t(size_t,
+						    PAGE_SIZE - page_off, left);
+				l = copy_page_to_iter(pages[k++], page_off,
+						      copy, i);
+				off += l;
+				left -= l;
+				if (l < copy)
+					break;
+			}
+		}
+		ceph_release_page_vector(pages, num_pages);
+	}
+
+	if (off > iocb->ki_pos) {
+		ret = off - iocb->ki_pos;
+		iocb->ki_pos = off;
+	}
+
+	dout("sync_read result %d\n", ret);
+	return ret;
+}
+
+/*
+ * Write commit request unsafe callback, called to tell us when a
+ * request is unsafe (that is, in flight--has been handed to the
+ * messenger to send to its target osd).  It is called again when
+ * we've received a response message indicating the request is
+ * "safe" (its CEPH_OSD_FLAG_ONDISK flag is set), or when a request
+ * is completed early (and unsuccessfully) due to a timeout or
+ * interrupt.
+ *
+ * This is used if we requested both an ACK and ONDISK commit reply
+ * from the OSD.
+ */
+static void ceph_sync_write_unsafe(struct ceph_osd_request *req, bool unsafe)
+{
+	struct ceph_inode_info *ci = ceph_inode(req->r_inode);
+
+	dout("%s %p tid %llu %ssafe\n", __func__, req, req->r_tid,
+		unsafe ? "un" : "");
+	if (unsafe) {
+		ceph_get_cap_refs(ci, CEPH_CAP_FILE_WR);
+		spin_lock(&ci->i_unsafe_lock);
+		list_add_tail(&req->r_unsafe_item,
+			      &ci->i_unsafe_writes);
+		spin_unlock(&ci->i_unsafe_lock);
+	} else {
+		spin_lock(&ci->i_unsafe_lock);
+		list_del_init(&req->r_unsafe_item);
+		spin_unlock(&ci->i_unsafe_lock);
+		ceph_put_cap_refs(ci, CEPH_CAP_FILE_WR);
+	}
+}
+
+
+/*
+ * Synchronous write, straight from __user pointer or user pages.
+ *
+ * If write spans object boundary, just do multiple writes.  (For a
+ * correct atomic write, we should e.g. take write locks on all
+ * objects, rollback on failure, etc.)
+ */
+static ssize_t
+ceph_sync_direct_write(struct kiocb *iocb, struct iov_iter *from, loff_t pos)
+{
+	struct file *file = iocb->ki_filp;
+	struct inode *inode = file_inode(file);
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
+	struct ceph_snap_context *snapc;
+	struct ceph_vino vino;
+	struct ceph_osd_request *req;
+	struct page **pages;
+	int num_pages;
+	int written = 0;
+	int flags;
+	int check_caps = 0;
+	int ret;
+	struct timespec mtime = CURRENT_TIME;
+	size_t count = iov_iter_count(from);
+
+	if (ceph_snap(file_inode(file)) != CEPH_NOSNAP)
+		return -EROFS;
+
+	dout("sync_direct_write on file %p %lld~%u\n", file, pos,
+	     (unsigned)count);
+
+	ret = filemap_write_and_wait_range(inode->i_mapping, pos, pos + count);
+	if (ret < 0)
+		return ret;
+
+	ret = invalidate_inode_pages2_range(inode->i_mapping,
+					    pos >> PAGE_CACHE_SHIFT,
+					    (pos + count) >> PAGE_CACHE_SHIFT);
+	if (ret < 0)
+		dout("invalidate_inode_pages2_range returned %d\n", ret);
+
+	flags = CEPH_OSD_FLAG_ORDERSNAP |
+		CEPH_OSD_FLAG_ONDISK |
+		CEPH_OSD_FLAG_WRITE;
+
+	while (iov_iter_count(from) > 0) {
+		u64 len = iov_iter_single_seg_count(from);
+		size_t start;
+		ssize_t n;
+
+		snapc = ci->i_snap_realm->cached_context;
+		vino = ceph_vino(inode);
+		req = ceph_osdc_new_request(&fsc->client->osdc, &ci->i_layout,
+					    vino, pos, &len, 0,
+					    2,/*include a 'startsync' command*/
+					    CEPH_OSD_OP_WRITE, flags, snapc,
+					    ci->i_truncate_seq,
+					    ci->i_truncate_size,
+					    false);
+		if (IS_ERR(req)) {
+			ret = PTR_ERR(req);
+			break;
+		}
+
+		osd_req_op_init(req, 1, CEPH_OSD_OP_STARTSYNC);
+
+		n = iov_iter_get_pages_alloc(from, &pages, len, &start);
+		if (unlikely(n < 0)) {
+			ret = n;
+			ceph_osdc_put_request(req);
+			break;
+		}
+
+		num_pages = (n + start + PAGE_SIZE - 1) / PAGE_SIZE;
+		/*
+		 * throw out any page cache pages in this range. this
+		 * may block.
+		 */
+		truncate_inode_pages_range(inode->i_mapping, pos,
+				   (pos+n) | (PAGE_CACHE_SIZE-1));
+		osd_req_op_extent_osd_data_pages(req, 0, pages, n, start,
+						false, false);
+
+		/* BUG_ON(vino.snap != CEPH_NOSNAP); */
+		ceph_osdc_build_request(req, pos, snapc, vino.snap, &mtime);
+
+		ret = ceph_osdc_start_request(&fsc->client->osdc, req, false);
+		if (!ret)
+			ret = ceph_osdc_wait_request(&fsc->client->osdc, req);
+
+		ceph_put_page_vector(pages, num_pages, false);
+
+		ceph_osdc_put_request(req);
+		if (ret)
+			break;
+		pos += n;
+		written += n;
+		iov_iter_advance(from, n);
+
+		if (pos > i_size_read(inode)) {
+			check_caps = ceph_inode_set_size(inode, pos);
+			if (check_caps)
+				ceph_check_caps(ceph_inode(inode),
+						CHECK_CAPS_AUTHONLY,
+						NULL);
+		}
+	}
+
+	if (ret != -EOLDSNAPC && written > 0) {
+		iocb->ki_pos = pos;
+		ret = written;
+	}
+	return ret;
+}
+
+
+/*
+ * Synchronous write, straight from __user pointer or user pages.
+ *
+ * If write spans object boundary, just do multiple writes.  (For a
+ * correct atomic write, we should e.g. take write locks on all
+ * objects, rollback on failure, etc.)
+ */
+static ssize_t
+ceph_sync_write(struct kiocb *iocb, struct iov_iter *from, loff_t pos)
+{
+	struct file *file = iocb->ki_filp;
+	struct inode *inode = file_inode(file);
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
+	struct ceph_snap_context *snapc;
+	struct ceph_vino vino;
+	struct ceph_osd_request *req;
+	struct page **pages;
+	u64 len;
+	int num_pages;
+	int written = 0;
+	int flags;
+	int check_caps = 0;
+	int ret;
+	struct timespec mtime = CURRENT_TIME;
+	size_t count = iov_iter_count(from);
+
+	if (ceph_snap(file_inode(file)) != CEPH_NOSNAP)
+		return -EROFS;
+
+	dout("sync_write on file %p %lld~%u\n", file, pos, (unsigned)count);
+
+	ret = filemap_write_and_wait_range(inode->i_mapping, pos, pos + count);
+	if (ret < 0)
+		return ret;
+
+	ret = invalidate_inode_pages2_range(inode->i_mapping,
+					    pos >> PAGE_CACHE_SHIFT,
+					    (pos + count) >> PAGE_CACHE_SHIFT);
+	if (ret < 0)
+		dout("invalidate_inode_pages2_range returned %d\n", ret);
+
+	flags = CEPH_OSD_FLAG_ORDERSNAP |
+		CEPH_OSD_FLAG_ONDISK |
+		CEPH_OSD_FLAG_WRITE |
+		CEPH_OSD_FLAG_ACK;
+
+	while ((len = iov_iter_count(from)) > 0) {
+		size_t left;
+		int n;
+
+		snapc = ci->i_snap_realm->cached_context;
+		vino = ceph_vino(inode);
+		req = ceph_osdc_new_request(&fsc->client->osdc, &ci->i_layout,
+					    vino, pos, &len, 0, 1,
+					    CEPH_OSD_OP_WRITE, flags, snapc,
+					    ci->i_truncate_seq,
+					    ci->i_truncate_size,
+					    false);
+		if (IS_ERR(req)) {
+			ret = PTR_ERR(req);
+			break;
+		}
+
+		/*
+		 * write from beginning of first page,
+		 * regardless of io alignment
+		 */
+		num_pages = (len + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+
+		pages = ceph_alloc_page_vector(num_pages, GFP_NOFS);
+		if (IS_ERR(pages)) {
+			ret = PTR_ERR(pages);
+			goto out;
+		}
+
+		left = len;
+		for (n = 0; n < num_pages; n++) {
+			size_t plen = min_t(size_t, left, PAGE_SIZE);
+			ret = copy_page_from_iter(pages[n], 0, plen, from);
+			if (ret != plen) {
+				ret = -EFAULT;
+				break;
+			}
+			left -= ret;
+		}
+
+		if (ret < 0) {
+			ceph_release_page_vector(pages, num_pages);
+			goto out;
+		}
+
+		/* get a second commit callback */
+		req->r_unsafe_callback = ceph_sync_write_unsafe;
+		req->r_inode = inode;
+
+		osd_req_op_extent_osd_data_pages(req, 0, pages, len, 0,
+						false, true);
+
+		/* BUG_ON(vino.snap != CEPH_NOSNAP); */
+		ceph_osdc_build_request(req, pos, snapc, vino.snap, &mtime);
+
+		ret = ceph_osdc_start_request(&fsc->client->osdc, req, false);
+		if (!ret)
+			ret = ceph_osdc_wait_request(&fsc->client->osdc, req);
+
+out:
+		ceph_osdc_put_request(req);
+		if (ret == 0) {
+			pos += len;
+			written += len;
+
+			if (pos > i_size_read(inode)) {
+				check_caps = ceph_inode_set_size(inode, pos);
+				if (check_caps)
+					ceph_check_caps(ceph_inode(inode),
+							CHECK_CAPS_AUTHONLY,
+							NULL);
+			}
+		} else
+			break;
+	}
+
+	if (ret != -EOLDSNAPC && written > 0) {
+		ret = written;
+		iocb->ki_pos = pos;
+	}
+	return ret;
+}
+
+/*
+ * Wrap generic_file_aio_read with checks for cap bits on the inode.
+ * Atomically grab references, so that those bits are not released
+ * back to the MDS mid-read.
+ *
+ * Hmm, the sync read case isn't actually async... should it be?
+ */
+static ssize_t ceph_read_iter(struct kiocb *iocb, struct iov_iter *to)
+{
+	struct file *filp = iocb->ki_filp;
+	struct ceph_file_info *fi = filp->private_data;
+	size_t len = iov_iter_count(to);
+	struct inode *inode = file_inode(filp);
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	struct page *pinned_page = NULL;
+	ssize_t ret;
+	int want, got = 0;
+	int retry_op = 0, read = 0;
+
+again:
+	dout("aio_read %p %llx.%llx %llu~%u trying to get caps on %p\n",
+	     inode, ceph_vinop(inode), iocb->ki_pos, (unsigned)len, inode);
+
+	if (fi->fmode & CEPH_FILE_MODE_LAZY)
+		want = CEPH_CAP_FILE_CACHE | CEPH_CAP_FILE_LAZYIO;
+	else
+		want = CEPH_CAP_FILE_CACHE;
+	ret = ceph_get_caps(ci, CEPH_CAP_FILE_RD, want, -1, &got, &pinned_page);
+	if (ret < 0)
+		return ret;
+
+	if ((got & (CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO)) == 0 ||
+	    (iocb->ki_flags & IOCB_DIRECT) ||
+	    (fi->flags & CEPH_F_SYNC)) {
+
+		dout("aio_sync_read %p %llx.%llx %llu~%u got cap refs on %s\n",
+		     inode, ceph_vinop(inode), iocb->ki_pos, (unsigned)len,
+		     ceph_cap_string(got));
+
+		if (ci->i_inline_version == CEPH_INLINE_NONE) {
+			/* hmm, this isn't really async... */
+			ret = ceph_sync_read(iocb, to, &retry_op);
+		} else {
+			retry_op = READ_INLINE;
+		}
+	} else {
+		dout("aio_read %p %llx.%llx %llu~%u got cap refs on %s\n",
+		     inode, ceph_vinop(inode), iocb->ki_pos, (unsigned)len,
+		     ceph_cap_string(got));
+
+		ret = generic_file_read_iter(iocb, to);
+	}
+	dout("aio_read %p %llx.%llx dropping cap refs on %s = %d\n",
+	     inode, ceph_vinop(inode), ceph_cap_string(got), (int)ret);
+	if (pinned_page) {
+		page_cache_release(pinned_page);
+		pinned_page = NULL;
+	}
+	ceph_put_cap_refs(ci, got);
+	if (retry_op && ret >= 0) {
+		int statret;
+		struct page *page = NULL;
+		loff_t i_size;
+		if (retry_op == READ_INLINE) {
+			page = __page_cache_alloc(GFP_NOFS);
+			if (!page)
+				return -ENOMEM;
+		}
+
+		statret = __ceph_do_getattr(inode, page,
+					    CEPH_STAT_CAP_INLINE_DATA, !!page);
+		if (statret < 0) {
+			 __free_page(page);
+			if (statret == -ENODATA) {
+				BUG_ON(retry_op != READ_INLINE);
+				goto again;
+			}
+			return statret;
+		}
+
+		i_size = i_size_read(inode);
+		if (retry_op == READ_INLINE) {
+			BUG_ON(ret > 0 || read > 0);
+			if (iocb->ki_pos < i_size &&
+			    iocb->ki_pos < PAGE_CACHE_SIZE) {
+				loff_t end = min_t(loff_t, i_size,
+						   iocb->ki_pos + len);
+				end = min_t(loff_t, end, PAGE_CACHE_SIZE);
+				if (statret < end)
+					zero_user_segment(page, statret, end);
+				ret = copy_page_to_iter(page,
+						iocb->ki_pos & ~PAGE_MASK,
+						end - iocb->ki_pos, to);
+				iocb->ki_pos += ret;
+				read += ret;
+			}
+			if (iocb->ki_pos < i_size && read < len) {
+				size_t zlen = min_t(size_t, len - read,
+						    i_size - iocb->ki_pos);
+				ret = iov_iter_zero(zlen, to);
+				iocb->ki_pos += ret;
+				read += ret;
+			}
+			__free_pages(page, 0);
+			return read;
+		}
+
+		/* hit EOF or hole? */
+		if (retry_op == CHECK_EOF && iocb->ki_pos < i_size &&
+		    ret < len) {
+			dout("sync_read hit hole, ppos %lld < size %lld"
+			     ", reading more\n", iocb->ki_pos,
+			     inode->i_size);
+
+			read += ret;
+			len -= ret;
+			retry_op = 0;
+			goto again;
+		}
+	}
+
+	if (ret >= 0)
+		ret += read;
+
+	return ret;
+}
+
+/*
+ * Take cap references to avoid releasing caps to MDS mid-write.
+ *
+ * If we are synchronous, and write with an old snap context, the OSD
+ * may return EOLDSNAPC.  In that case, retry the write.. _after_
+ * dropping our cap refs and allowing the pending snap to logically
+ * complete _before_ this write occurs.
+ *
+ * If we are near ENOSPC, write synchronously.
+ */
+static ssize_t ceph_write_iter(struct kiocb *iocb, struct iov_iter *from)
+{
+	struct file *file = iocb->ki_filp;
+	struct ceph_file_info *fi = file->private_data;
+	struct inode *inode = file_inode(file);
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	struct ceph_osd_client *osdc =
+		&ceph_sb_to_client(inode->i_sb)->client->osdc;
+	ssize_t count, written = 0;
+	int err, want, got;
+	loff_t pos;
+
+	if (ceph_snap(inode) != CEPH_NOSNAP)
+		return -EROFS;
+
+	mutex_lock(&inode->i_mutex);
+
+	/* We can write back this queue in page reclaim */
+	current->backing_dev_info = inode_to_bdi(inode);
+
+	err = generic_write_checks(iocb, from);
+	if (err <= 0)
+		goto out;
+
+	pos = iocb->ki_pos;
+	count = iov_iter_count(from);
+	err = file_remove_suid(file);
+	if (err)
+		goto out;
+
+	err = file_update_time(file);
+	if (err)
+		goto out;
+
+	if (ci->i_inline_version != CEPH_INLINE_NONE) {
+		err = ceph_uninline_data(file, NULL);
+		if (err < 0)
+			goto out;
+	}
+
+retry_snap:
+	if (ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_FULL)) {
+		err = -ENOSPC;
+		goto out;
+	}
+
+	dout("aio_write %p %llx.%llx %llu~%zd getting caps. i_size %llu\n",
+	     inode, ceph_vinop(inode), pos, count, inode->i_size);
+	if (fi->fmode & CEPH_FILE_MODE_LAZY)
+		want = CEPH_CAP_FILE_BUFFER | CEPH_CAP_FILE_LAZYIO;
+	else
+		want = CEPH_CAP_FILE_BUFFER;
+	got = 0;
+	err = ceph_get_caps(ci, CEPH_CAP_FILE_WR, want, pos + count,
+			    &got, NULL);
+	if (err < 0)
+		goto out;
+
+	dout("aio_write %p %llx.%llx %llu~%zd got cap refs on %s\n",
+	     inode, ceph_vinop(inode), pos, count, ceph_cap_string(got));
+
+	if ((got & (CEPH_CAP_FILE_BUFFER|CEPH_CAP_FILE_LAZYIO)) == 0 ||
+	    (iocb->ki_flags & IOCB_DIRECT) || (fi->flags & CEPH_F_SYNC)) {
+		struct iov_iter data;
+		mutex_unlock(&inode->i_mutex);
+		/* we might need to revert back to that point */
+		data = *from;
+		if (iocb->ki_flags & IOCB_DIRECT)
+			written = ceph_sync_direct_write(iocb, &data, pos);
+		else
+			written = ceph_sync_write(iocb, &data, pos);
+		if (written == -EOLDSNAPC) {
+			dout("aio_write %p %llx.%llx %llu~%u"
+				"got EOLDSNAPC, retrying\n",
+				inode, ceph_vinop(inode),
+				pos, (unsigned)count);
+			mutex_lock(&inode->i_mutex);
+			goto retry_snap;
+		}
+		if (written > 0)
+			iov_iter_advance(from, written);
+	} else {
+		loff_t old_size = inode->i_size;
+		/*
+		 * No need to acquire the i_truncate_mutex. Because
+		 * the MDS revokes Fwb caps before sending truncate
+		 * message to us. We can't get Fwb cap while there
+		 * are pending vmtruncate. So write and vmtruncate
+		 * can not run at the same time
+		 */
+		written = generic_perform_write(file, from, pos);
+		if (likely(written >= 0))
+			iocb->ki_pos = pos + written;
+		if (inode->i_size > old_size)
+			ceph_fscache_update_objectsize(inode);
+		mutex_unlock(&inode->i_mutex);
+	}
+
+	if (written >= 0) {
+		int dirty;
+		spin_lock(&ci->i_ceph_lock);
+		ci->i_inline_version = CEPH_INLINE_NONE;
+		dirty = __ceph_mark_dirty_caps(ci, CEPH_CAP_FILE_WR);
+		spin_unlock(&ci->i_ceph_lock);
+		if (dirty)
+			__mark_inode_dirty(inode, dirty);
+	}
+
+	dout("aio_write %p %llx.%llx %llu~%u  dropping cap refs on %s\n",
+	     inode, ceph_vinop(inode), pos, (unsigned)count,
+	     ceph_cap_string(got));
+	ceph_put_cap_refs(ci, got);
+
+	if (written >= 0 &&
+	    ((file->f_flags & O_SYNC) || IS_SYNC(file->f_mapping->host) ||
+	     ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_NEARFULL))) {
+		err = vfs_fsync_range(file, pos, pos + written - 1, 1);
+		if (err < 0)
+			written = err;
+	}
+
+	goto out_unlocked;
+
+out:
+	mutex_unlock(&inode->i_mutex);
+out_unlocked:
+	current->backing_dev_info = NULL;
+	return written ? written : err;
+}
+
+/*
+ * llseek.  be sure to verify file size on SEEK_END.
+ */
+static loff_t ceph_llseek(struct file *file, loff_t offset, int whence)
+{
+	struct inode *inode = file->f_mapping->host;
+	int ret;
+
+	mutex_lock(&inode->i_mutex);
+
+	if (whence == SEEK_END || whence == SEEK_DATA || whence == SEEK_HOLE) {
+		ret = ceph_do_getattr(inode, CEPH_STAT_CAP_SIZE, false);
+		if (ret < 0) {
+			offset = ret;
+			goto out;
+		}
+	}
+
+	switch (whence) {
+	case SEEK_END:
+		offset += inode->i_size;
+		break;
+	case SEEK_CUR:
+		/*
+		 * Here we special-case the lseek(fd, 0, SEEK_CUR)
+		 * position-querying operation.  Avoid rewriting the "same"
+		 * f_pos value back to the file because a concurrent read(),
+		 * write() or lseek() might have altered it
+		 */
+		if (offset == 0) {
+			offset = file->f_pos;
+			goto out;
+		}
+		offset += file->f_pos;
+		break;
+	case SEEK_DATA:
+		if (offset >= inode->i_size) {
+			ret = -ENXIO;
+			goto out;
+		}
+		break;
+	case SEEK_HOLE:
+		if (offset >= inode->i_size) {
+			ret = -ENXIO;
+			goto out;
+		}
+		offset = inode->i_size;
+		break;
+	}
+
+	offset = vfs_setpos(file, offset, inode->i_sb->s_maxbytes);
+
+out:
+	mutex_unlock(&inode->i_mutex);
+	return offset;
+}
+
+static inline void ceph_zero_partial_page(
+	struct inode *inode, loff_t offset, unsigned size)
+{
+	struct page *page;
+	pgoff_t index = offset >> PAGE_CACHE_SHIFT;
+
+	page = find_lock_page(inode->i_mapping, index);
+	if (page) {
+		wait_on_page_writeback(page);
+		zero_user(page, offset & (PAGE_CACHE_SIZE - 1), size);
+		unlock_page(page);
+		page_cache_release(page);
+	}
+}
+
+static void ceph_zero_pagecache_range(struct inode *inode, loff_t offset,
+				      loff_t length)
+{
+	loff_t nearly = round_up(offset, PAGE_CACHE_SIZE);
+	if (offset < nearly) {
+		loff_t size = nearly - offset;
+		if (length < size)
+			size = length;
+		ceph_zero_partial_page(inode, offset, size);
+		offset += size;
+		length -= size;
+	}
+	if (length >= PAGE_CACHE_SIZE) {
+		loff_t size = round_down(length, PAGE_CACHE_SIZE);
+		truncate_pagecache_range(inode, offset, offset + size - 1);
+		offset += size;
+		length -= size;
+	}
+	if (length)
+		ceph_zero_partial_page(inode, offset, length);
+}
+
+static int ceph_zero_partial_object(struct inode *inode,
+				    loff_t offset, loff_t *length)
+{
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
+	struct ceph_osd_request *req;
+	int ret = 0;
+	loff_t zero = 0;
+	int op;
+
+	if (!length) {
+		op = offset ? CEPH_OSD_OP_DELETE : CEPH_OSD_OP_TRUNCATE;
+		length = &zero;
+	} else {
+		op = CEPH_OSD_OP_ZERO;
+	}
+
+	req = ceph_osdc_new_request(&fsc->client->osdc, &ci->i_layout,
+					ceph_vino(inode),
+					offset, length,
+					0, 1, op,
+					CEPH_OSD_FLAG_WRITE |
+					CEPH_OSD_FLAG_ONDISK,
+					NULL, 0, 0, false);
+	if (IS_ERR(req)) {
+		ret = PTR_ERR(req);
+		goto out;
+	}
+
+	ceph_osdc_build_request(req, offset, NULL, ceph_vino(inode).snap,
+				&inode->i_mtime);
+
+	ret = ceph_osdc_start_request(&fsc->client->osdc, req, false);
+	if (!ret) {
+		ret = ceph_osdc_wait_request(&fsc->client->osdc, req);
+		if (ret == -ENOENT)
+			ret = 0;
+	}
+	ceph_osdc_put_request(req);
+
+out:
+	return ret;
+}
+
+static int ceph_zero_objects(struct inode *inode, loff_t offset, loff_t length)
+{
+	int ret = 0;
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	s32 stripe_unit = ceph_file_layout_su(ci->i_layout);
+	s32 stripe_count = ceph_file_layout_stripe_count(ci->i_layout);
+	s32 object_size = ceph_file_layout_object_size(ci->i_layout);
+	u64 object_set_size = object_size * stripe_count;
+	u64 nearly, t;
+
+	/* round offset up to next period boundary */
+	nearly = offset + object_set_size - 1;
+	t = nearly;
+	nearly -= do_div(t, object_set_size);
+
+	while (length && offset < nearly) {
+		loff_t size = length;
+		ret = ceph_zero_partial_object(inode, offset, &size);
+		if (ret < 0)
+			return ret;
+		offset += size;
+		length -= size;
+	}
+	while (length >= object_set_size) {
+		int i;
+		loff_t pos = offset;
+		for (i = 0; i < stripe_count; ++i) {
+			ret = ceph_zero_partial_object(inode, pos, NULL);
+			if (ret < 0)
+				return ret;
+			pos += stripe_unit;
+		}
+		offset += object_set_size;
+		length -= object_set_size;
+	}
+	while (length) {
+		loff_t size = length;
+		ret = ceph_zero_partial_object(inode, offset, &size);
+		if (ret < 0)
+			return ret;
+		offset += size;
+		length -= size;
+	}
+	return ret;
+}
+
+static long ceph_fallocate(struct file *file, int mode,
+				loff_t offset, loff_t length)
+{
+	struct ceph_file_info *fi = file->private_data;
+	struct inode *inode = file_inode(file);
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	struct ceph_osd_client *osdc =
+		&ceph_inode_to_client(inode)->client->osdc;
+	int want, got = 0;
+	int dirty;
+	int ret = 0;
+	loff_t endoff = 0;
+	loff_t size;
+
+	if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
+		return -EOPNOTSUPP;
+
+	if (!S_ISREG(inode->i_mode))
+		return -EOPNOTSUPP;
+
+	mutex_lock(&inode->i_mutex);
+
+	if (ceph_snap(inode) != CEPH_NOSNAP) {
+		ret = -EROFS;
+		goto unlock;
+	}
+
+	if (ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_FULL) &&
+		!(mode & FALLOC_FL_PUNCH_HOLE)) {
+		ret = -ENOSPC;
+		goto unlock;
+	}
+
+	if (ci->i_inline_version != CEPH_INLINE_NONE) {
+		ret = ceph_uninline_data(file, NULL);
+		if (ret < 0)
+			goto unlock;
+	}
+
+	size = i_size_read(inode);
+	if (!(mode & FALLOC_FL_KEEP_SIZE))
+		endoff = offset + length;
+
+	if (fi->fmode & CEPH_FILE_MODE_LAZY)
+		want = CEPH_CAP_FILE_BUFFER | CEPH_CAP_FILE_LAZYIO;
+	else
+		want = CEPH_CAP_FILE_BUFFER;
+
+	ret = ceph_get_caps(ci, CEPH_CAP_FILE_WR, want, endoff, &got, NULL);
+	if (ret < 0)
+		goto unlock;
+
+	if (mode & FALLOC_FL_PUNCH_HOLE) {
+		if (offset < size)
+			ceph_zero_pagecache_range(inode, offset, length);
+		ret = ceph_zero_objects(inode, offset, length);
+	} else if (endoff > size) {
+		truncate_pagecache_range(inode, size, -1);
+		if (ceph_inode_set_size(inode, endoff))
+			ceph_check_caps(ceph_inode(inode),
+				CHECK_CAPS_AUTHONLY, NULL);
+	}
+
+	if (!ret) {
+		spin_lock(&ci->i_ceph_lock);
+		ci->i_inline_version = CEPH_INLINE_NONE;
+		dirty = __ceph_mark_dirty_caps(ci, CEPH_CAP_FILE_WR);
+		spin_unlock(&ci->i_ceph_lock);
+		if (dirty)
+			__mark_inode_dirty(inode, dirty);
+	}
+
+	ceph_put_cap_refs(ci, got);
+unlock:
+	mutex_unlock(&inode->i_mutex);
+	return ret;
+}
+
+const struct file_operations ceph_file_fops = {
+	.open = ceph_open,
+	.release = ceph_release,
+	.llseek = ceph_llseek,
+	.read_iter = ceph_read_iter,
+	.write_iter = ceph_write_iter,
+	.mmap = ceph_mmap,
+	.fsync = ceph_fsync,
+	.lock = ceph_lock,
+	.flock = ceph_flock,
+	.splice_read = generic_file_splice_read,
+	.splice_write = iter_file_splice_write,
+	.unlocked_ioctl = ceph_ioctl,
+	.compat_ioctl	= ceph_ioctl,
+	.fallocate	= ceph_fallocate,
+};
+