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ceph: simplify+fix atomic_open

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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: Sage Weil <sage@inktank.com>
This commit is contained in:
Sage Weil 2012-07-31 11:27:36 -07:00
parent 1a9b4993b7
commit 5ef50c3bec
3 changed files with 40 additions and 66 deletions
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38
fs/ceph/dir.c
View file

@ -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).

62
fs/ceph/file.c
View file

@ -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 @@ int ceph_open(struct inode *inode, struct file *file)
/*
* 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 (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 = finish_open(file, req->r_dentry, ceph_open, opened);
out:
ret = ceph_finish_lookup(req, dentry, 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);
}
out_err:
ceph_mdsc_put_request(req);
dout("ceph_lookup_open result=%p\n", ret);
if (IS_ERR(ret))
return PTR_ERR(ret);
dput(ret);
dout("atomic_open result=%d\n", err);
return err;
}

6
fs/ceph/super.h
View file

@ -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 */