ceph: file operations (124e68e7) · Commits · 戴 / test

fs/ceph/file.c

0 → 100644

+904 −0

Original line number	Diff line number	Diff line
		#include "ceph_debug.h"

		#include <linux/sched.h>
		#include <linux/file.h>
		#include <linux/namei.h>
		#include <linux/writeback.h>

		#include "super.h"
		#include "mds_client.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_client *client = ceph_sb_to_client(sb);
		struct ceph_mds_client *mdsc = &client->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);
		req->r_args.open.preferred = -1;
		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;

		switch (inode->i_mode & S_IFMT) {
		case S_IFREG:
		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 the filp already has private_data, that means the file was
		* already opened by intent during lookup, and we do nothing.
		*
		* 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_client *client = ceph_sb_to_client(inode->i_sb);
		struct ceph_mds_client *mdsc = &client->mdsc;
		struct ceph_mds_request *req;
		struct ceph_file_info *cf = file->private_data;
		struct inode *parent_inode = file->f_dentry->d_parent->d_inode;
		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(&inode->i_lock);
		__ceph_get_fmode(ci, fmode);
		spin_unlock(&inode->i_lock);
		return ceph_init_file(inode, file, fmode);
		}

		/*
		* No need to block if we have any caps. Update wanted set
		* asynchronously.
		*/
		spin_lock(&inode->i_lock);
		if (__ceph_is_any_real_caps(ci)) {
		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(&inode->i_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(&inode->i_lock);
		return ceph_init_file(inode, file, fmode);
		}
		spin_unlock(&inode->i_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 = igrab(inode);
		req->r_num_caps = 1;
		err = ceph_mdsc_do_request(mdsc, parent_inode, req);
		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 this succeeds, but some subsequent check in the vfs
		* may_open() fails, the struct *file gets cleaned up (i.e.
		* ceph_release gets called). So fear not!
		*/
		/*
		* flags
		* path_lookup_open -> LOOKUP_OPEN
		* path_lookup_create -> LOOKUP_OPEN\|LOOKUP_CREATE
		*/
		struct dentry ceph_lookup_open(struct inode dir, struct dentry *dentry,
		struct nameidata *nd, int mode,
		int locked_dir)
		{
		struct ceph_client *client = ceph_sb_to_client(dir->i_sb);
		struct ceph_mds_client *mdsc = &client->mdsc;
		struct file *file = nd->intent.open.file;
		struct inode *parent_inode = get_dentry_parent_inode(file->f_dentry);
		struct ceph_mds_request *req;
		int err;
		int flags = nd->intent.open.flags - 1; /* silly vfs! */

		dout("ceph_lookup_open dentry %p '%.*s' flags %d mode 0%o\n",
		dentry, dentry->d_name.len, dentry->d_name.name, flags, mode);

		/* do the open */
		req = prepare_open_request(dir->i_sb, flags, mode);
		if (IS_ERR(req))
		return ERR_PTR(PTR_ERR(req));
		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;
		}
		req->r_locked_dir = dir; /* caller holds dir->i_mutex */
		err = ceph_mdsc_do_request(mdsc, parent_inode, req);
		dentry = ceph_finish_lookup(req, dentry, err);
		if (!err && (flags & O_CREAT) && !req->r_reply_info.head->is_dentry)
		err = ceph_handle_notrace_create(dir, dentry);
		if (!err)
		err = ceph_init_file(req->r_dentry->d_inode, file,
		req->r_fmode);
		ceph_mdsc_put_request(req);
		dout("ceph_lookup_open result=%p\n", dentry);
		return dentry;
		}

		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);
		return 0;
		}

		/*
		* build a vector of user pages
		*/
		static struct page *get_direct_page_vector(const char __user data,
		int num_pages,
		loff_t off, size_t len)
		{
		struct page **pages;
		int rc;

		pages = kmalloc(sizeof(pages) num_pages, GFP_NOFS);
		if (!pages)
		return ERR_PTR(-ENOMEM);

		down_read(&current->mm->mmap_sem);
		rc = get_user_pages(current, current->mm, (unsigned long)data,
		num_pages, 0, 0, pages, NULL);
		up_read(&current->mm->mmap_sem);
		if (rc < 0)
		goto fail;
		return pages;

		fail:
		kfree(pages);
		return ERR_PTR(rc);
		}

		static void put_page_vector(struct page **pages, int num_pages)
		{
		int i;

		for (i = 0; i < num_pages; i++)
		put_page(pages[i]);
		kfree(pages);
		}

		void ceph_release_page_vector(struct page **pages, int num_pages)
		{
		int i;

		for (i = 0; i < num_pages; i++)
		__free_pages(pages[i], 0);
		kfree(pages);
		}

		/*
		* allocate a vector new pages
		*/
		static struct page **alloc_page_vector(int num_pages)
		{
		struct page **pages;
		int i;

		pages = kmalloc(sizeof(pages) num_pages, GFP_NOFS);
		if (!pages)
		return ERR_PTR(-ENOMEM);
		for (i = 0; i < num_pages; i++) {
		pages[i] = alloc_page(GFP_NOFS);
		if (pages[i] == NULL) {
		ceph_release_page_vector(pages, i);
		return ERR_PTR(-ENOMEM);
		}
		}
		return pages;
		}

		/*
		* copy user data into a page vector
		*/
		static int copy_user_to_page_vector(struct page **pages,
		const char __user *data,
		loff_t off, size_t len)
		{
		int i = 0;
		int po = off & ~PAGE_CACHE_MASK;
		int left = len;
		int l, bad;

		while (left > 0) {
		l = min_t(int, PAGE_CACHE_SIZE-po, left);
		bad = copy_from_user(page_address(pages[i]) + po, data, l);
		if (bad == l)
		return -EFAULT;
		data += l - bad;
		left -= l - bad;
		if (po) {
		po += l - bad;
		if (po == PAGE_CACHE_SIZE)
		po = 0;
		}
		}
		return len;
		}

		/*
		* copy user data from a page vector into a user pointer
		*/
		static int copy_page_vector_to_user(struct page *pages, char __user data,
		loff_t off, size_t len)
		{
		int i = 0;
		int po = off & ~PAGE_CACHE_MASK;
		int left = len;
		int l, bad;

		while (left > 0) {
		l = min_t(int, left, PAGE_CACHE_SIZE-po);
		bad = copy_to_user(data, page_address(pages[i]) + po, l);
		if (bad == l)
		return -EFAULT;
		data += l - bad;
		left -= l - bad;
		if (po) {
		po += l - bad;
		if (po == PAGE_CACHE_SIZE)
		po = 0;
		}
		i++;
		}
		return len;
		}

		/*
		* Zero an extent within a page vector. Offset is relative to the
		* start of the first page.
		*/
		static void zero_page_vector_range(int off, int len, struct page **pages)
		{
		int i = off >> PAGE_CACHE_SHIFT;

		dout("zero_page_vector_page %u~%u\n", off, len);
		BUG_ON(len < PAGE_CACHE_SIZE);

		/* leading partial page? */
		if (off & ~PAGE_CACHE_MASK) {
		dout("zeroing %d %p head from %d\n", i, pages[i],
		(int)(off & ~PAGE_CACHE_MASK));
		zero_user_segment(pages[i], off & ~PAGE_CACHE_MASK,
		PAGE_CACHE_SIZE);
		off += PAGE_CACHE_SIZE;
		off &= PAGE_CACHE_MASK;
		i++;
		}
		while (len >= PAGE_CACHE_SIZE) {
		dout("zeroing %d %p\n", i, pages[i]);
		zero_user_segment(pages[i], 0, PAGE_CACHE_SIZE);
		off += PAGE_CACHE_SIZE;
		len -= PAGE_CACHE_SIZE;
		i++;
		}
		/* trailing partial page? */
		if (len) {
		dout("zeroing %d %p tail to %d\n", i, pages[i], (int)len);
		zero_user_segment(pages[i], 0, len);
		}
		}


		/*
		* 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)
		{
		struct ceph_client *client = ceph_inode_to_client(inode);
		struct ceph_inode_info *ci = ceph_inode(inode);
		u64 pos, this_len;
		int page_off = off & ~PAGE_CACHE_SIZE; /* first byte's offset in page */
		int left, 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;

		more:
		this_len = left;
		ret = ceph_osdc_readpages(&client->osdc, ceph_vino(inode),
		&ci->i_layout, pos, &this_len,
		ci->i_truncate_seq,
		ci->i_truncate_size,
		page_pos, pages_left);
		hit_stripe = this_len < left;
		was_short = ret >= 0 && ret < this_len;
		if (ret == -ENOENT)
		ret = 0;
		dout("striped_read %llu~%u (read %u) got %d%s%s\n", pos, left, read,
		ret, hit_stripe ? " HITSTRIPE" : "", was_short ? " SHORT" : "");

		if (ret > 0) {
		int didpages =
		((pos & ~PAGE_CACHE_MASK) + ret) >> PAGE_CACHE_SHIFT;

		if (read < pos - off) {
		dout(" zero gap %llu to %llu\n", off + read, pos);
		zero_page_vector_range(page_off + read,
		pos - off - read, pages);
		}
		pos += ret;
		read = pos - off;
		left -= ret;
		page_pos += didpages;
		pages_left -= didpages;

		/* hit stripe? */
		if (left && hit_stripe)
		goto more;
		}

		if (was_short) {
		/* was original extent fully inside i_size? */
		if (pos + left <= inode->i_size) {
		dout("zero tail\n");
		zero_page_vector_range(page_off + read, len - read,
		pages);
		goto out;
		}

		/* check i_size */
		ret = ceph_do_getattr(inode, CEPH_STAT_CAP_SIZE);
		if (ret < 0)
		goto out;

		/* hit EOF? */
		if (pos >= inode->i_size)
		goto out;

		goto more;
		}

		out:
		if (ret >= 0)
		ret = read;
		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 file file, char __user data,
		unsigned len, loff_t *poff)
		{
		struct inode *inode = file->f_dentry->d_inode;
		struct page **pages;
		u64 off = *poff;
		int num_pages = calc_pages_for(off, len);
		int ret;

		dout("sync_read on file %p %llu~%u %s\n", file, off, len,
		(file->f_flags & O_DIRECT) ? "O_DIRECT" : "");

		if (file->f_flags & O_DIRECT) {
		pages = get_direct_page_vector(data, num_pages, off, len);

		/*
		* flush any page cache pages in this range. this
		* will make concurrent normal and O_DIRECT io slow,
		* but it will at least behave sensibly when they are
		* in sequence.
		*/
		filemap_write_and_wait(inode->i_mapping);
		} else {
		pages = alloc_page_vector(num_pages);
		}
		if (IS_ERR(pages))
		return PTR_ERR(pages);

		ret = striped_read(inode, off, len, pages, num_pages);

		if (ret >= 0 && (file->f_flags & O_DIRECT) == 0)
		ret = copy_page_vector_to_user(pages, data, off, ret);
		if (ret >= 0)
		*poff = off + ret;

		if (file->f_flags & O_DIRECT)
		put_page_vector(pages, num_pages);
		else
		ceph_release_page_vector(pages, num_pages);
		dout("sync_read result %d\n", ret);
		return ret;
		}

		/*
		* Write commit callback, called if we requested both an ACK and
		* ONDISK commit reply from the OSD.
		*/
		static void sync_write_commit(struct ceph_osd_request *req,
		struct ceph_msg *msg)
		{
		struct ceph_inode_info *ci = ceph_inode(req->r_inode);

		dout("sync_write_commit %p tid %llu\n", req, req->r_tid);
		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
		* O_DIRECT).
		*
		* 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 file file, const char __user data,
		size_t left, loff_t *offset)
		{
		struct inode *inode = file->f_dentry->d_inode;
		struct ceph_inode_info *ci = ceph_inode(inode);
		struct ceph_client *client = ceph_inode_to_client(inode);
		struct ceph_osd_request *req;
		struct page **pages;
		int num_pages;
		long long unsigned pos;
		u64 len;
		int written = 0;
		int flags;
		int do_sync = 0;
		int check_caps = 0;
		int ret;
		struct timespec mtime = CURRENT_TIME;

		if (ceph_snap(file->f_dentry->d_inode) != CEPH_NOSNAP)
		return -EROFS;

		dout("sync_write on file %p %lld~%u %s\n", file, *offset,
		(unsigned)left, (file->f_flags & O_DIRECT) ? "O_DIRECT" : "");

		if (file->f_flags & O_APPEND)
		pos = i_size_read(inode);
		else
		pos = *offset;

		flags = CEPH_OSD_FLAG_ORDERSNAP \|
		CEPH_OSD_FLAG_ONDISK \|
		CEPH_OSD_FLAG_WRITE;
		if ((file->f_flags & (O_SYNC\|O_DIRECT)) == 0)
		flags \|= CEPH_OSD_FLAG_ACK;
		else
		do_sync = 1;

		/*
		* we may need to do multiple writes here if we span an object
		* boundary. this isn't atomic, unfortunately. :(
		*/
		more:
		len = left;
		req = ceph_osdc_new_request(&client->osdc, &ci->i_layout,
		ceph_vino(inode), pos, &len,
		CEPH_OSD_OP_WRITE, flags,
		ci->i_snap_realm->cached_context,
		do_sync,
		ci->i_truncate_seq, ci->i_truncate_size,
		&mtime, false, 2);
		if (IS_ERR(req))
		return PTR_ERR(req);

		num_pages = calc_pages_for(pos, len);

		if (file->f_flags & O_DIRECT) {
		pages = get_direct_page_vector(data, num_pages, pos, len);
		if (IS_ERR(pages)) {
		ret = PTR_ERR(pages);
		goto out;
		}

		/*
		* throw out any page cache pages in this range. this
		* may block.
		*/
		truncate_inode_pages_range(inode->i_mapping, pos, pos+len);
		} else {
		pages = alloc_page_vector(num_pages);
		if (IS_ERR(pages)) {
		ret = PTR_ERR(pages);
		goto out;
		}
		ret = copy_user_to_page_vector(pages, data, pos, len);
		if (ret < 0) {
		ceph_release_page_vector(pages, num_pages);
		goto out;
		}

		if ((file->f_flags & O_SYNC) == 0) {
		/* get a second commit callback */
		req->r_safe_callback = sync_write_commit;
		req->r_own_pages = 1;
		}
		}
		req->r_pages = pages;
		req->r_num_pages = num_pages;
		req->r_inode = inode;

		ret = ceph_osdc_start_request(&client->osdc, req, false);
		if (!ret) {
		if (req->r_safe_callback) {
		/*
		* Add to inode unsafe list only after we
		* start_request so that a tid has been assigned.
		*/
		spin_lock(&ci->i_unsafe_lock);
		list_add(&ci->i_unsafe_writes, &req->r_unsafe_item);
		spin_unlock(&ci->i_unsafe_lock);
		ceph_get_cap_refs(ci, CEPH_CAP_FILE_WR);
		}
		ret = ceph_osdc_wait_request(&client->osdc, req);
		}

		if (file->f_flags & O_DIRECT)
		put_page_vector(pages, num_pages);
		else if (file->f_flags & O_SYNC)
		ceph_release_page_vector(pages, num_pages);

		out:
		ceph_osdc_put_request(req);
		if (ret == 0) {
		pos += len;
		written += len;
		left -= len;
		if (left)
		goto more;

		ret = written;
		*offset = pos;
		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);
		}
		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_aio_read(struct kiocb iocb, const struct iovec iov,
		unsigned long nr_segs, loff_t pos)
		{
		struct file *filp = iocb->ki_filp;
		loff_t *ppos = &iocb->ki_pos;
		size_t len = iov->iov_len;
		struct inode *inode = filp->f_dentry->d_inode;
		struct ceph_inode_info *ci = ceph_inode(inode);
		ssize_t ret;
		int got = 0;

		dout("aio_read %p %llx.%llx %llu~%u trying to get caps on %p\n",
		inode, ceph_vinop(inode), pos, (unsigned)len, inode);
		__ceph_do_pending_vmtruncate(inode);
		ret = ceph_get_caps(ci, CEPH_CAP_FILE_RD, CEPH_CAP_FILE_CACHE,
		&got, -1);
		if (ret < 0)
		goto out;
		dout("aio_read %p %llx.%llx %llu~%u got cap refs on %s\n",
		inode, ceph_vinop(inode), pos, (unsigned)len,
		ceph_cap_string(got));

		if ((got & CEPH_CAP_FILE_CACHE) == 0 \|\|
		(iocb->ki_filp->f_flags & O_DIRECT) \|\|
		(inode->i_sb->s_flags & MS_SYNCHRONOUS))
		/* hmm, this isn't really async... */
		ret = ceph_sync_read(filp, iov->iov_base, len, ppos);
		else
		ret = generic_file_aio_read(iocb, iov, nr_segs, pos);

		out:
		dout("aio_read %p %llx.%llx dropping cap refs on %s = %d\n",
		inode, ceph_vinop(inode), ceph_cap_string(got), (int)ret);
		ceph_put_cap_refs(ci, got);
		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_aio_write(struct kiocb iocb, const struct iovec iov,
		unsigned long nr_segs, loff_t pos)
		{
		struct file *file = iocb->ki_filp;
		struct inode *inode = file->f_dentry->d_inode;
		struct ceph_inode_info *ci = ceph_inode(inode);
		struct ceph_osd_client *osdc = &ceph_client(inode->i_sb)->osdc;
		loff_t endoff = pos + iov->iov_len;
		int got = 0;
		int ret;

		if (ceph_snap(inode) != CEPH_NOSNAP)
		return -EROFS;

		retry_snap:
		if (ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_FULL))
		return -ENOSPC;
		__ceph_do_pending_vmtruncate(inode);
		dout("aio_write %p %llx.%llx %llu~%u getting caps. i_size %llu\n",
		inode, ceph_vinop(inode), pos, (unsigned)iov->iov_len,
		inode->i_size);
		ret = ceph_get_caps(ci, CEPH_CAP_FILE_WR, CEPH_CAP_FILE_BUFFER,
		&got, endoff);
		if (ret < 0)
		goto out;

		dout("aio_write %p %llx.%llx %llu~%u got cap refs on %s\n",
		inode, ceph_vinop(inode), pos, (unsigned)iov->iov_len,
		ceph_cap_string(got));

		if ((got & CEPH_CAP_FILE_BUFFER) == 0 \|\|
		(iocb->ki_filp->f_flags & O_DIRECT) \|\|
		(inode->i_sb->s_flags & MS_SYNCHRONOUS)) {
		ret = ceph_sync_write(file, iov->iov_base, iov->iov_len,
		&iocb->ki_pos);
		} else {
		ret = generic_file_aio_write(iocb, iov, nr_segs, pos);

		if ((ret >= 0 \|\| ret == -EIOCBQUEUED) &&
		((file->f_flags & O_SYNC) \|\| IS_SYNC(file->f_mapping->host)
		\|\| ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_NEARFULL)))
		ret = vfs_fsync_range(file, file->f_path.dentry,
		pos, pos + ret - 1, 1);
		}
		if (ret >= 0) {
		spin_lock(&inode->i_lock);
		__ceph_mark_dirty_caps(ci, CEPH_CAP_FILE_WR);
		spin_unlock(&inode->i_lock);
		}

		out:
		dout("aio_write %p %llx.%llx %llu~%u dropping cap refs on %s\n",
		inode, ceph_vinop(inode), pos, (unsigned)iov->iov_len,
		ceph_cap_string(got));
		ceph_put_cap_refs(ci, got);

		if (ret == -EOLDSNAPC) {
		dout("aio_write %p %llx.%llx %llu~%u got EOLDSNAPC, retrying\n",
		inode, ceph_vinop(inode), pos, (unsigned)iov->iov_len);
		goto retry_snap;
		}

		return ret;
		}

		/*
		* llseek. be sure to verify file size on SEEK_END.
		*/
		static loff_t ceph_llseek(struct file *file, loff_t offset, int origin)
		{
		struct inode *inode = file->f_mapping->host;
		int ret;

		mutex_lock(&inode->i_mutex);
		__ceph_do_pending_vmtruncate(inode);
		switch (origin) {
		case SEEK_END:
		ret = ceph_do_getattr(inode, CEPH_STAT_CAP_SIZE);
		if (ret < 0) {
		offset = ret;
		goto out;
		}
		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;
		}

		if (offset < 0 \|\| offset > inode->i_sb->s_maxbytes) {
		offset = -EINVAL;
		goto out;
		}

		/* Special lock needed here? */
		if (offset != file->f_pos) {
		file->f_pos = offset;
		file->f_version = 0;
		}

		out:
		mutex_unlock(&inode->i_mutex);
		return offset;
		}

		const struct file_operations ceph_file_fops = {
		.open = ceph_open,
		.release = ceph_release,
		.llseek = ceph_llseek,
		.read = do_sync_read,
		.write = do_sync_write,
		.aio_read = ceph_aio_read,
		.aio_write = ceph_aio_write,
		.mmap = ceph_mmap,
		.fsync = ceph_fsync,
		.splice_read = generic_file_splice_read,
		.splice_write = generic_file_splice_write,
		.unlocked_ioctl = ceph_ioctl,
		.compat_ioctl = ceph_ioctl,
		};

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