GFS2: Add atomic_open support
I've restricted atomic_open to only operate on regular files, although
I still don't understand why atomic_open should not be possible also for
directories on GFS2. That can always be added in later though, if it
makes sense.
The ->atomic_open function can be passed negative dentries, which
in most cases means either ENOENT (->lookup) or a call to d_instantiate
(->create). In the GFS2 case though, we need to actually perform the
look up, since we do not know whether there has been a new inode created
on another node. The look up calls d_splice_alias which then tries to
rehash the dentry - so the solution here is to simply check for that
in d_splice_alias. The same issue is likely to affect any other cluster
filesystem implementing ->atomic_open
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "J. Bruce Fields" <bfields fieldses org>
Cc: Jeff Layton <jlayton@redhat.com>
diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c
index ede16ae7..bbb2715 100644
--- a/fs/gfs2/inode.c
+++ b/fs/gfs2/inode.c
@@ -535,6 +535,7 @@
* gfs2_create_inode - Create a new inode
* @dir: The parent directory
* @dentry: The new dentry
+ * @file: If non-NULL, the file which is being opened
* @mode: The permissions on the new inode
* @dev: For device nodes, this is the device number
* @symname: For symlinks, this is the link destination
@@ -544,8 +545,9 @@
*/
static int gfs2_create_inode(struct inode *dir, struct dentry *dentry,
+ struct file *file,
umode_t mode, dev_t dev, const char *symname,
- unsigned int size, int excl)
+ unsigned int size, int excl, int *opened)
{
const struct qstr *name = &dentry->d_name;
struct gfs2_holder ghs[2];
@@ -553,6 +555,7 @@
struct gfs2_inode *dip = GFS2_I(dir), *ip;
struct gfs2_sbd *sdp = GFS2_SB(&dip->i_inode);
struct gfs2_glock *io_gl;
+ struct dentry *d;
int error;
u32 aflags = 0;
int arq;
@@ -579,9 +582,20 @@
inode = gfs2_dir_search(dir, &dentry->d_name, !S_ISREG(mode) || excl);
error = PTR_ERR(inode);
if (!IS_ERR(inode)) {
+ d = d_splice_alias(inode, dentry);
+ error = 0;
+ if (file && !IS_ERR(d)) {
+ if (d == NULL)
+ d = dentry;
+ if (S_ISREG(inode->i_mode))
+ error = finish_open(file, d, gfs2_open_common, opened);
+ else
+ error = finish_no_open(file, d);
+ }
gfs2_glock_dq_uninit(ghs);
- d_instantiate(dentry, inode);
- return 0;
+ if (IS_ERR(d))
+ return PTR_RET(d);
+ return error;
} else if (error != -ENOENT) {
goto fail_gunlock;
}
@@ -679,10 +693,12 @@
goto fail_gunlock3;
mark_inode_dirty(inode);
+ d_instantiate(dentry, inode);
+ if (file)
+ error = finish_open(file, dentry, gfs2_open_common, opened);
gfs2_glock_dq_uninit(ghs);
gfs2_glock_dq_uninit(ghs + 1);
- d_instantiate(dentry, inode);
- return 0;
+ return error;
fail_gunlock3:
gfs2_glock_dq_uninit(ghs + 1);
@@ -722,36 +738,56 @@
static int gfs2_create(struct inode *dir, struct dentry *dentry,
umode_t mode, bool excl)
{
- return gfs2_create_inode(dir, dentry, S_IFREG | mode, 0, NULL, 0, excl);
+ return gfs2_create_inode(dir, dentry, NULL, S_IFREG | mode, 0, NULL, 0, excl, NULL);
}
/**
- * gfs2_lookup - Look up a filename in a directory and return its inode
+ * __gfs2_lookup - Look up a filename in a directory and return its inode
* @dir: The directory inode
* @dentry: The dentry of the new inode
- * @nd: passed from Linux VFS, ignored by us
+ * @file: File to be opened
+ * @opened: atomic_open flags
*
- * Called by the VFS layer. Lock dir and call gfs2_lookupi()
*
* Returns: errno
*/
-static struct dentry *gfs2_lookup(struct inode *dir, struct dentry *dentry,
- unsigned int flags)
+static struct dentry *__gfs2_lookup(struct inode *dir, struct dentry *dentry,
+ struct file *file, int *opened)
{
- struct inode *inode = gfs2_lookupi(dir, &dentry->d_name, 0);
- if (inode && !IS_ERR(inode)) {
- struct gfs2_glock *gl = GFS2_I(inode)->i_gl;
- struct gfs2_holder gh;
- int error;
- error = gfs2_glock_nq_init(gl, LM_ST_SHARED, LM_FLAG_ANY, &gh);
- if (error) {
- iput(inode);
- return ERR_PTR(error);
- }
- gfs2_glock_dq_uninit(&gh);
+ struct inode *inode;
+ struct dentry *d;
+ struct gfs2_holder gh;
+ struct gfs2_glock *gl;
+ int error;
+
+ inode = gfs2_lookupi(dir, &dentry->d_name, 0);
+ if (!inode)
+ return NULL;
+ if (IS_ERR(inode))
+ return ERR_CAST(inode);
+
+ gl = GFS2_I(inode)->i_gl;
+ error = gfs2_glock_nq_init(gl, LM_ST_SHARED, LM_FLAG_ANY, &gh);
+ if (error) {
+ iput(inode);
+ return ERR_PTR(error);
}
- return d_splice_alias(inode, dentry);
+
+ d = d_splice_alias(inode, dentry);
+ if (file && S_ISREG(inode->i_mode))
+ error = finish_open(file, dentry, gfs2_open_common, opened);
+
+ gfs2_glock_dq_uninit(&gh);
+ if (error)
+ return ERR_PTR(error);
+ return d;
+}
+
+static struct dentry *gfs2_lookup(struct inode *dir, struct dentry *dentry,
+ unsigned flags)
+{
+ return __gfs2_lookup(dir, dentry, NULL, NULL);
}
/**
@@ -1069,7 +1105,7 @@
if (size > sdp->sd_sb.sb_bsize - sizeof(struct gfs2_dinode) - 1)
return -ENAMETOOLONG;
- return gfs2_create_inode(dir, dentry, S_IFLNK | S_IRWXUGO, 0, symname, size, 0);
+ return gfs2_create_inode(dir, dentry, NULL, S_IFLNK | S_IRWXUGO, 0, symname, size, 0, NULL);
}
/**
@@ -1085,7 +1121,7 @@
{
struct gfs2_sbd *sdp = GFS2_SB(dir);
unsigned dsize = sdp->sd_sb.sb_bsize - sizeof(struct gfs2_dinode);
- return gfs2_create_inode(dir, dentry, S_IFDIR | mode, 0, NULL, dsize, 0);
+ return gfs2_create_inode(dir, dentry, NULL, S_IFDIR | mode, 0, NULL, dsize, 0, NULL);
}
/**
@@ -1100,7 +1136,43 @@
static int gfs2_mknod(struct inode *dir, struct dentry *dentry, umode_t mode,
dev_t dev)
{
- return gfs2_create_inode(dir, dentry, mode, dev, NULL, 0, 0);
+ return gfs2_create_inode(dir, dentry, NULL, mode, dev, NULL, 0, 0, NULL);
+}
+
+/**
+ * gfs2_atomic_open - Atomically open a file
+ * @dir: The directory
+ * @dentry: The proposed new entry
+ * @file: The proposed new struct file
+ * @flags: open flags
+ * @mode: File mode
+ * @opened: Flag to say whether the file has been opened or not
+ *
+ * Returns: error code or 0 for success
+ */
+
+static int gfs2_atomic_open(struct inode *dir, struct dentry *dentry,
+ struct file *file, unsigned flags,
+ umode_t mode, int *opened)
+{
+ struct dentry *d;
+ bool excl = !!(flags & O_EXCL);
+
+ d = __gfs2_lookup(dir, dentry, file, opened);
+ if (IS_ERR(d))
+ return PTR_ERR(d);
+ if (d == NULL)
+ d = dentry;
+ if (d->d_inode) {
+ if (!(*opened & FILE_OPENED))
+ return finish_no_open(file, d);
+ return 0;
+ }
+
+ if (!(flags & O_CREAT))
+ return -ENOENT;
+
+ return gfs2_create_inode(dir, dentry, file, S_IFREG | mode, 0, NULL, 0, excl, opened);
}
/*
@@ -1780,6 +1852,7 @@
.removexattr = gfs2_removexattr,
.fiemap = gfs2_fiemap,
.get_acl = gfs2_get_acl,
+ .atomic_open = gfs2_atomic_open,
};
const struct inode_operations gfs2_symlink_iops = {