Commit 5ef50c3b authored by Sage Weil's avatar Sage Weil
Browse files

ceph: simplify+fix atomic_open 



The initial ->atomic_open op was carried over from the old intent code,
which was incomplete and didn't really work.  Replace it with a fresh
method.  In particular:

 * always attempt to do an atomic open+lookup, both for the create case
   and for lookups of existing files.
 * fix symlink handling by returning 1 to the VFS so that we can follow
   the link to its destination. This fixes a longstanding ceph bug (#2392).

Signed-off-by: default avatarSage Weil <sage@inktank.com>
parent 1a9b4993

fs/ceph/dir.c

+0 −38
Original line number Diff line number Diff line
@@ -633,44 +633,6 @@ static struct dentry *ceph_lookup(struct inode *dir, struct dentry *dentry, 
	return dentry;

}



int ceph_atomic_open(struct inode *dir, struct dentry *dentry,

		     struct file *file, unsigned flags, umode_t mode,

		     int *opened)

{

	int err;

	struct dentry *res = NULL;



	if (!(flags & O_CREAT)) {

		if (dentry->d_name.len > NAME_MAX)

			return -ENAMETOOLONG;



		err = ceph_init_dentry(dentry);

		if (err < 0)

			return err;



		return ceph_lookup_open(dir, dentry, file, flags, mode, opened);

	}



	if (d_unhashed(dentry)) {

		res = ceph_lookup(dir, dentry, 0);

		if (IS_ERR(res))

			return PTR_ERR(res);



		if (res)

			dentry = res;

	}



	/* We don't deal with positive dentries here */

	if (dentry->d_inode)

		return finish_no_open(file, res);



	*opened |= FILE_CREATED;

	err = ceph_lookup_open(dir, dentry, file, flags, mode, opened);

	dput(res);



	return err;

}



/*

 * If we do a create but get no trace back from the MDS, follow up with

 * a lookup (the VFS expects us to link up the provided dentry).

fs/ceph/file.c

+37 −25
Original line number Diff line number Diff line
@@ -4,6 +4,7 @@ 
#include <linux/sched.h>

#include <linux/slab.h>

#include <linux/file.h>

#include <linux/mount.h>

#include <linux/namei.h>

#include <linux/writeback.h>
@@ -106,9 +107,6 @@ static int ceph_init_file(struct inode *inode, struct file *file, int fmode) 
}



/*

 * 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)
@@ -207,24 +205,29 @@ out: 




/*

 * 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!

 * 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_lookup_open(struct inode *dir, struct dentry *dentry,

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 *ret;

	struct dentry *dn;

	int err;



	dout("ceph_lookup_open dentry %p '%.*s' flags %d mode 0%o\n",

	     dentry, dentry->d_name.len, dentry->d_name.name, flags, mode);

	dout("atomic_open %p dentry %p '%.*s' %s flags %d mode 0%o\n",

	     dir, dentry, dentry->d_name.len, dentry->d_name.name,

	     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;



	/* do the open */

	req = prepare_open_request(dir->i_sb, flags, mode);
@@ -241,22 +244,31 @@ int ceph_lookup_open(struct inode *dir, struct dentry *dentry, 
				   (flags & (O_CREAT|O_TRUNC)) ? dir : NULL,

				   req);

	err = ceph_handle_snapdir(req, dentry, err);

	if (err)

		goto out;

	if ((flags & O_CREAT) && !req->r_reply_info.head->is_dentry)

	if (err == 0 && (flags & O_CREAT) && !req->r_reply_info.head->is_dentry)

		err = ceph_handle_notrace_create(dir, dentry);

	if (err)

		goto out;

	err = finish_open(file, req->r_dentry, ceph_open, opened);

out:

	ret = ceph_finish_lookup(req, dentry, err);

	ceph_mdsc_put_request(req);

	dout("ceph_lookup_open result=%p\n", ret);



	if (IS_ERR(ret))

		return PTR_ERR(ret);

	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_err;

	if (dn || dentry->d_inode == NULL || S_ISLNK(dentry->d_inode->i_mode)) {

		/* 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);

		err = finish_open(file, dentry, ceph_open, opened);

	}



	dput(ret);

out_err:

	ceph_mdsc_put_request(req);

	dout("atomic_open result=%d\n", err);

	return err;

}

fs/ceph/super.h

+3 −3
Original line number Diff line number Diff line
@@ -806,9 +806,9 @@ extern int ceph_copy_from_page_vector(struct page **pages, 
				    loff_t off, size_t len);

extern struct page **ceph_alloc_page_vector(int num_pages, gfp_t flags);

extern int ceph_open(struct inode *inode, struct file *file);

extern int ceph_lookup_open(struct inode *dir, struct dentry *dentry,

			     struct file *od, unsigned flags,

			     umode_t mode, int *opened);

extern int ceph_atomic_open(struct inode *dir, struct dentry *dentry,

			    struct file *file, unsigned flags, umode_t mode,

			    int *opened);

extern int ceph_release(struct inode *inode, struct file *filp);



/* dir.c */

CRA Git | Maintained and supported by SUSTech CRA and CCSE