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Subject[PATCH 04/14] fs/ntfs3: atomic_open implementation
From
Added ntfs_atomic_open function.
Relaxed locking in ntfs_create_inode.

Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
---
fs/ntfs3/inode.c | 24 ++++++++++--
fs/ntfs3/namei.c | 100 +++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 120 insertions(+), 4 deletions(-)

diff --git a/fs/ntfs3/inode.c b/fs/ntfs3/inode.c
index df0d30a3218a..405afb54cc19 100644
--- a/fs/ntfs3/inode.c
+++ b/fs/ntfs3/inode.c
@@ -1183,6 +1183,18 @@ ntfs_create_reparse_buffer(struct ntfs_sb_info *sbi, const char *symname,
return ERR_PTR(err);
}

+/*
+ * ntfs_create_inode
+ *
+ * Helper function for:
+ * - ntfs_create
+ * - ntfs_mknod
+ * - ntfs_symlink
+ * - ntfs_mkdir
+ * - ntfs_atomic_open
+ *
+ * NOTE: if fnd != NULL (ntfs_atomic_open) then @dir is locked
+ */
struct inode *ntfs_create_inode(struct user_namespace *mnt_userns,
struct inode *dir, struct dentry *dentry,
const struct cpu_str *uni, umode_t mode,
@@ -1212,7 +1224,8 @@ struct inode *ntfs_create_inode(struct user_namespace *mnt_userns,
struct REPARSE_DATA_BUFFER *rp = NULL;
bool rp_inserted = false;

- ni_lock_dir(dir_ni);
+ if (!fnd)
+ ni_lock_dir(dir_ni);

dir_root = indx_get_root(&dir_ni->dir, dir_ni, NULL, NULL);
if (!dir_root) {
@@ -1575,7 +1588,8 @@ struct inode *ntfs_create_inode(struct user_namespace *mnt_userns,
goto out6;

/* Unlock parent directory before ntfs_init_acl. */
- ni_unlock(dir_ni);
+ if (!fnd)
+ ni_unlock(dir_ni);

inode->i_generation = le16_to_cpu(rec->seq);

@@ -1635,7 +1649,8 @@ struct inode *ntfs_create_inode(struct user_namespace *mnt_userns,
out7:

/* Undo 'indx_insert_entry'. */
- ni_lock_dir(dir_ni);
+ if (!fnd)
+ ni_lock_dir(dir_ni);
indx_delete_entry(&dir_ni->dir, dir_ni, new_de + 1,
le16_to_cpu(new_de->key_size), sbi);
/* ni_unlock(dir_ni); will be called later. */
@@ -1663,7 +1678,8 @@ struct inode *ntfs_create_inode(struct user_namespace *mnt_userns,

out1:
if (err) {
- ni_unlock(dir_ni);
+ if (!fnd)
+ ni_unlock(dir_ni);
return ERR_PTR(err);
}

diff --git a/fs/ntfs3/namei.c b/fs/ntfs3/namei.c
index ff76389475ad..1af02d4f6b4d 100644
--- a/fs/ntfs3/namei.c
+++ b/fs/ntfs3/namei.c
@@ -8,6 +8,7 @@
#include <linux/fs.h>
#include <linux/nls.h>
#include <linux/ctype.h>
+#include <linux/posix_acl.h>

#include "debug.h"
#include "ntfs.h"
@@ -334,6 +335,104 @@ static int ntfs_rename(struct user_namespace *mnt_userns, struct inode *dir,
return err;
}

+/*
+ * ntfs_atomic_open
+ *
+ * inode_operations::atomic_open
+ */
+static int ntfs_atomic_open(struct inode *dir, struct dentry *dentry,
+ struct file *file, u32 flags, umode_t mode)
+{
+ int err;
+ struct inode *inode;
+ struct ntfs_fnd *fnd = NULL;
+ struct ntfs_inode *ni = ntfs_i(dir);
+ struct dentry *d = NULL;
+ struct cpu_str *uni = __getname();
+ bool locked = false;
+
+ if (!uni)
+ return -ENOMEM;
+
+ err = ntfs_nls_to_utf16(ni->mi.sbi, dentry->d_name.name,
+ dentry->d_name.len, uni, NTFS_NAME_LEN,
+ UTF16_HOST_ENDIAN);
+ if (err < 0)
+ goto out;
+
+#ifdef CONFIG_NTFS3_FS_POSIX_ACL
+ if (IS_POSIXACL(dir)) {
+ /*
+ * Load in cache current acl to avoid ni_lock(dir):
+ * ntfs_create_inode -> ntfs_init_acl -> posix_acl_create ->
+ * ntfs_get_acl -> ntfs_get_acl_ex -> ni_lock
+ */
+ struct posix_acl *p = get_acl(dir, ACL_TYPE_DEFAULT);
+
+ if (IS_ERR(p)) {
+ err = PTR_ERR(p);
+ goto out;
+ }
+ posix_acl_release(p);
+ }
+#endif
+
+ if (d_in_lookup(dentry)) {
+ ni_lock_dir(ni);
+ locked = true;
+ fnd = fnd_get();
+ if (!fnd) {
+ err = -ENOMEM;
+ goto out1;
+ }
+
+ d = d_splice_alias(dir_search_u(dir, uni, fnd), dentry);
+ if (IS_ERR(d)) {
+ err = PTR_ERR(d);
+ d = NULL;
+ goto out2;
+ }
+
+ if (d)
+ dentry = d;
+ }
+
+ if (!(flags & O_CREAT) || d_really_is_positive(dentry)) {
+ err = finish_no_open(file, d);
+ goto out2;
+ }
+
+ file->f_mode |= FMODE_CREATED;
+
+ /*
+ * fnd contains tree's path to insert to.
+ * If fnd is not NULL then dir is locked.
+ */
+
+ /*
+ * Unfortunately I don't know how to get here correct 'struct nameidata *nd'
+ * or 'struct user_namespace *mnt_userns'.
+ * See atomic_open in fs/namei.c.
+ * This is why xfstest/633 failed.
+ * Looks like ntfs_atomic_open must accept 'struct user_namespace *mnt_userns' as argument.
+ */
+
+ inode = ntfs_create_inode(&init_user_ns, dir, dentry, uni, mode, 0,
+ NULL, 0, fnd);
+ err = IS_ERR(inode) ? PTR_ERR(inode)
+ : finish_open(file, dentry, ntfs_file_open);
+ dput(d);
+
+out2:
+ fnd_put(fnd);
+out1:
+ if (locked)
+ ni_unlock(ni);
+out:
+ __putname(uni);
+ return err;
+}
+
struct dentry *ntfs3_get_parent(struct dentry *child)
{
struct inode *inode = d_inode(child);
@@ -504,6 +603,7 @@ const struct inode_operations ntfs_dir_inode_operations = {
.setattr = ntfs3_setattr,
.getattr = ntfs_getattr,
.listxattr = ntfs_listxattr,
+ .atomic_open = ntfs_atomic_open,
.fiemap = ntfs_fiemap,
};

--
2.37.0

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