cifs: implement i_op->atomic_open()

Add an ->atomic_open implementation which replaces the atomic lookup+open+create
operation implemented via ->lookup and ->create operations.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
CC: Steve French <sfrench@samba.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 243 insertions, 198 deletions

diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c
index ec4e9a2a12f8..7a3dcd15d681 100644
--- a/fs/cifs/dir.c
+++ b/fs/cifs/dir.c
@@ -133,108 +133,141 @@ cifs_bp_rename_retry:
         return full_path;
 }
 
+/*
+ * Don't allow the separator character in a path component.
+ * The VFS will not allow "/", but "\" is allowed by posix.
+ */
+static int
+check_name(struct dentry *direntry)
+{
+        struct cifs_sb_info *cifs_sb = CIFS_SB(direntry->d_sb);
+        int i;
+
+        if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_POSIX_PATHS)) {
+                for (i = 0; i < direntry->d_name.len; i++) {
+                        if (direntry->d_name.name[i] == '\\') {
+                                cFYI(1, "Invalid file name");
+                                return -EINVAL;
+                        }
+                }
+        }
+        return 0;
+}
+
+
 /* Inode operations in similar order to how they appear in Linux file fs.h */
 
-int
-cifs_create(struct inode *inode, struct dentry *direntry, umode_t mode,
-                struct nameidata *nd)
+static int cifs_do_create(struct inode *inode, struct dentry *direntry,
+                          int xid, struct tcon_link *tlink, unsigned oflags,
+                          umode_t mode, __u32 *oplock, __u16 *fileHandle,
+                          bool *created)
 {
         int rc = -ENOENT;
-        int xid;
         int create_options = CREATE_NOT_DIR;
-        __u32 oplock = 0;
-        int oflags;
-        /*
-         * BB below access is probably too much for mknod to request
-         *    but we have to do query and setpathinfo so requesting
-         *    less could fail (unless we want to request getatr and setatr
-         *    permissions (only).  At least for POSIX we do not have to
-         *    request so much.
-         */
-        int desiredAccess = GENERIC_READ | GENERIC_WRITE;
-        __u16 fileHandle;
-        struct cifs_sb_info *cifs_sb;
-        struct tcon_link *tlink;
-        struct cifs_tcon *tcon;
+        int desiredAccess;
+        struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
+        struct cifs_tcon *tcon = tlink_tcon(tlink);
         char *full_path = NULL;
         FILE_ALL_INFO *buf = NULL;
         struct inode *newinode = NULL;
-        int disposition = FILE_OVERWRITE_IF;
-
-        xid = GetXid();
-
-        cifs_sb = CIFS_SB(inode->i_sb);
-        tlink = cifs_sb_tlink(cifs_sb);
-        if (IS_ERR(tlink)) {
-                FreeXid(xid);
-                return PTR_ERR(tlink);
-        }
-        tcon = tlink_tcon(tlink);
+        int disposition;
 
+        *oplock = 0;
         if (tcon->ses->server->oplocks)
-                oplock = REQ_OPLOCK;
-
-        if (nd)
-                oflags = nd->intent.open.file->f_flags;
-        else
-                oflags = O_RDONLY | O_CREAT;
+                *oplock = REQ_OPLOCK;
 
         full_path = build_path_from_dentry(direntry);
         if (full_path == NULL) {
                 rc = -ENOMEM;
-                goto cifs_create_out;
+                goto out;
         }
 
         if (tcon->unix_ext && (tcon->ses->capabilities & CAP_UNIX) &&
+            !tcon->broken_posix_open &&
             (CIFS_UNIX_POSIX_PATH_OPS_CAP &
                         le64_to_cpu(tcon->fsUnixInfo.Capability))) {
                 rc = cifs_posix_open(full_path, &newinode,
-                        inode->i_sb, mode, oflags, &oplock, &fileHandle, xid);
-                /* EIO could indicate that (posix open) operation is not
-                   supported, despite what server claimed in capability
-                   negotiation.  EREMOTE indicates DFS junction, which is not
-                   handled in posix open */
-
-                if (rc == 0) {
-                        if (newinode == NULL) /* query inode info */
+                        inode->i_sb, mode, oflags, oplock, fileHandle, xid);
+                switch (rc) {
+                case 0:
+                        if (newinode == NULL) {
+                                /* query inode info */
                                 goto cifs_create_get_file_info;
-                        else /* success, no need to query */
-                                goto cifs_create_set_dentry;
-                } else if ((rc != -EIO) && (rc != -EREMOTE) &&
-                         (rc != -EOPNOTSUPP) && (rc != -EINVAL))
-                        goto cifs_create_out;
-                /* else fallthrough to retry, using older open call, this is
-                   case where server does not support this SMB level, and
-                   falsely claims capability (also get here for DFS case
-                   which should be rare for path not covered on files) */
-        }
+                        }
 
-        if (nd) {
-                /* if the file is going to stay open, then we
-                   need to set the desired access properly */
-                desiredAccess = 0;
-                if (OPEN_FMODE(oflags) & FMODE_READ)
-                        desiredAccess |= GENERIC_READ; /* is this too little? */
-                if (OPEN_FMODE(oflags) & FMODE_WRITE)
-                        desiredAccess |= GENERIC_WRITE;
-
-                if ((oflags & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL))
-                        disposition = FILE_CREATE;
-                else if ((oflags & (O_CREAT | O_TRUNC)) == (O_CREAT | O_TRUNC))
-                        disposition = FILE_OVERWRITE_IF;
-                else if ((oflags & O_CREAT) == O_CREAT)
-                        disposition = FILE_OPEN_IF;
-                else
-                        cFYI(1, "Create flag not set in create function");
+                        if (!S_ISREG(newinode->i_mode)) {
+                                /*
+                                 * The server may allow us to open things like
+                                 * FIFOs, but the client isn't set up to deal
+                                 * with that. If it's not a regular file, just
+                                 * close it and proceed as if it were a normal
+                                 * lookup.
+                                 */
+                                CIFSSMBClose(xid, tcon, *fileHandle);
+                                goto cifs_create_get_file_info;
+                        }
+                        /* success, no need to query */
+                        goto cifs_create_set_dentry;
+
+                case -ENOENT:
+                        goto cifs_create_get_file_info;
+
+                case -EIO:
+                case -EINVAL:
+                        /*
+                         * EIO could indicate that (posix open) operation is not
+                         * supported, despite what server claimed in capability
+                         * negotiation.
+                         *
+                         * POSIX open in samba versions 3.3.1 and earlier could
+                         * incorrectly fail with invalid parameter.
+                         */
+                        tcon->broken_posix_open = true;
+                        break;
+
+                case -EREMOTE:
+                case -EOPNOTSUPP:
+                        /*
+                         * EREMOTE indicates DFS junction, which is not handled
+                         * in posix open.  If either that or op not supported
+                         * returned, follow the normal lookup.
+                         */
+                        break;
+
+                default:
+                        goto out;
+                }
+                /*
+                 * fallthrough to retry, using older open call, this is case
+                 * where server does not support this SMB level, and falsely
+                 * claims capability (also get here for DFS case which should be
+                 * rare for path not covered on files)
+                 */
         }
 
+        desiredAccess = 0;
+        if (OPEN_FMODE(oflags) & FMODE_READ)
+                desiredAccess |= GENERIC_READ; /* is this too little? */
+        if (OPEN_FMODE(oflags) & FMODE_WRITE)
+                desiredAccess |= GENERIC_WRITE;
+
+        disposition = FILE_OVERWRITE_IF;
+        if ((oflags & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL))
+                disposition = FILE_CREATE;
+        else if ((oflags & (O_CREAT | O_TRUNC)) == (O_CREAT | O_TRUNC))
+                disposition = FILE_OVERWRITE_IF;
+        else if ((oflags & O_CREAT) == O_CREAT)
+                disposition = FILE_OPEN_IF;
+        else
+                cFYI(1, "Create flag not set in create function");
+
         /* BB add processing to set equivalent of mode - e.g. via CreateX with
            ACLs */
 
         buf = kmalloc(sizeof(FILE_ALL_INFO), GFP_KERNEL);
         if (buf == NULL) {
                 rc = -ENOMEM;
-                goto cifs_create_out;
+                goto out;
         }
 
         /*
@@ -250,7 +283,7 @@ cifs_create(struct inode *inode, struct dentry *direntry, umode_t mode,
         if (tcon->ses->capabilities & CAP_NT_SMBS)
                 rc = CIFSSMBOpen(xid, tcon, full_path, disposition,
                          desiredAccess, create_options,
-                         &fileHandle, &oplock, buf, cifs_sb->local_nls,
+                         fileHandle, oplock, buf, cifs_sb->local_nls,
                          cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);
         else
                 rc = -EIO; /* no NT SMB support fall into legacy open below */
@@ -259,17 +292,17 @@ cifs_create(struct inode *inode, struct dentry *direntry, umode_t mode,
                 /* old server, retry the open legacy style */
                 rc = SMBLegacyOpen(xid, tcon, full_path, disposition,
                         desiredAccess, create_options,
-                        &fileHandle, &oplock, buf, cifs_sb->local_nls,
+                        fileHandle, oplock, buf, cifs_sb->local_nls,
                         cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);
         }
         if (rc) {
                 cFYI(1, "cifs_create returned 0x%x", rc);
-                goto cifs_create_out;
+                goto out;
         }
 
         /* If Open reported that we actually created a file
            then we now have to set the mode if possible */
-        if ((tcon->unix_ext) && (oplock & CIFS_CREATE_ACTION)) {
+        if ((tcon->unix_ext) && (*oplock & CIFS_CREATE_ACTION)) {
                 struct cifs_unix_set_info_args args = {
                                 .mode   = mode,
                                 .ctime  = NO_CHANGE_64,
@@ -278,6 +311,7 @@ cifs_create(struct inode *inode, struct dentry *direntry, umode_t mode,
                                 .device = 0,
                 };
 
+                *created = true;
                 if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SET_UID) {
                         args.uid = (__u64) current_fsuid();
                         if (inode->i_mode & S_ISGID)
@@ -288,7 +322,7 @@ cifs_create(struct inode *inode, struct dentry *direntry, umode_t mode,
                         args.uid = NO_CHANGE_64;
                         args.gid = NO_CHANGE_64;
                 }
-                CIFSSMBUnixSetFileInfo(xid, tcon, &args, fileHandle,
+                CIFSSMBUnixSetFileInfo(xid, tcon, &args, *fileHandle,
                                         current->tgid);
         } else {
                 /* BB implement mode setting via Windows security
@@ -305,11 +339,11 @@ cifs_create_get_file_info:
                                               inode->i_sb, xid);
         else {
                 rc = cifs_get_inode_info(&newinode, full_path, buf,
-                                         inode->i_sb, xid, &fileHandle);
+                                         inode->i_sb, xid, fileHandle);
                 if (newinode) {
                         if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_DYNPERM)
                                 newinode->i_mode = mode;
-                        if ((oplock & CIFS_CREATE_ACTION) &&
+                        if ((*oplock & CIFS_CREATE_ACTION) &&
                             (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SET_UID)) {
                                 newinode->i_uid = current_fsuid();
                                 if (inode->i_mode & S_ISGID)
@@ -321,37 +355,139 @@ cifs_create_get_file_info:
         }
 
 cifs_create_set_dentry:
-        if (rc == 0)
-                d_instantiate(direntry, newinode);
-        else
+        if (rc != 0) {
                 cFYI(1, "Create worked, get_inode_info failed rc = %d", rc);
+                goto out;
+        }
+        d_drop(direntry);
+        d_add(direntry, newinode);
 
-        if (newinode && nd) {
-                struct cifsFileInfo *pfile_info;
-                struct file *filp;
+        /* ENOENT for create?  How weird... */
+        rc = -ENOENT;
+        if (!newinode) {
+                CIFSSMBClose(xid, tcon, *fileHandle);
+                goto out;
+        }
+        rc = 0;
 
-                filp = lookup_instantiate_filp(nd, direntry, generic_file_open);
-                if (IS_ERR(filp)) {
-                        rc = PTR_ERR(filp);
-                        CIFSSMBClose(xid, tcon, fileHandle);
-                        goto cifs_create_out;
-                }
+out:
+        kfree(buf);
+        kfree(full_path);
+        return rc;
+}
 
-                pfile_info = cifs_new_fileinfo(fileHandle, filp, tlink, oplock);
-                if (pfile_info == NULL) {
-                        fput(filp);
-                        CIFSSMBClose(xid, tcon, fileHandle);
-                        rc = -ENOMEM;
-                }
-        } else {
+struct file *
+cifs_atomic_open(struct inode *inode, struct dentry *direntry,
+                 struct opendata *od, unsigned oflags, umode_t mode,
+                 bool *created)
+{
+        int rc;
+        int xid;
+        struct tcon_link *tlink;
+        struct cifs_tcon *tcon;
+        __u16 fileHandle;
+        __u32 oplock;
+        struct file *filp;
+        struct cifsFileInfo *pfile_info;
+
+        /* Posix open is only called (at lookup time) for file create now.  For
+         * opens (rather than creates), because we do not know if it is a file
+         * or directory yet, and current Samba no longer allows us to do posix
+         * open on dirs, we could end up wasting an open call on what turns out
+         * to be a dir. For file opens, we wait to call posix open till
+         * cifs_open.  It could be added to atomic_open in the future but the
+         * performance tradeoff of the extra network request when EISDIR or
+         * EACCES is returned would have to be weighed against the 50% reduction
+         * in network traffic in the other paths.
+         */
+        if (!(oflags & O_CREAT)) {
+                struct dentry *res = cifs_lookup(inode, direntry, NULL);
+                if (IS_ERR(res))
+                        return ERR_CAST(res);
+
+                finish_no_open(od, res);
+                return NULL;
+        }
+
+        rc = check_name(direntry);
+        if (rc)
+                return ERR_PTR(rc);
+
+        xid = GetXid();
+
+        cFYI(1, "parent inode = 0x%p name is: %s and dentry = 0x%p",
+             inode, direntry->d_name.name, direntry);
+
+        tlink = cifs_sb_tlink(CIFS_SB(inode->i_sb));
+        filp = ERR_CAST(tlink);
+        if (IS_ERR(tlink))
+                goto free_xid;
+
+        tcon = tlink_tcon(tlink);
+
+        rc = cifs_do_create(inode, direntry, xid, tlink, oflags, mode,
+                            &oplock, &fileHandle, created);
+
+        if (rc) {
+                filp = ERR_PTR(rc);
+                goto out;
+        }
+
+        filp = finish_open(od, direntry, generic_file_open);
+        if (IS_ERR(filp)) {
                 CIFSSMBClose(xid, tcon, fileHandle);
+                goto out;
         }
 
-cifs_create_out:
-        kfree(buf);
-        kfree(full_path);
+        pfile_info = cifs_new_fileinfo(fileHandle, filp, tlink, oplock);
+        if (pfile_info == NULL) {
+                CIFSSMBClose(xid, tcon, fileHandle);
+                fput(filp);
+                filp = ERR_PTR(-ENOMEM);
+        }
+
+out:
+        cifs_put_tlink(tlink);
+free_xid:
+        FreeXid(xid);
+        return filp;
+}
+
+int cifs_create(struct inode *inode, struct dentry *direntry, umode_t mode,
+                struct nameidata *nd)
+{
+        int rc;
+        int xid = GetXid();
+        /*
+         * BB below access is probably too much for mknod to request
+         *    but we have to do query and setpathinfo so requesting
+         *    less could fail (unless we want to request getatr and setatr
+         *    permissions (only).  At least for POSIX we do not have to
+         *    request so much.
+         */
+        unsigned oflags = O_EXCL | O_CREAT | O_RDWR;
+        struct tcon_link *tlink;
+        __u16 fileHandle;
+        __u32 oplock;
+        bool created = true;
+
+        cFYI(1, "cifs_create parent inode = 0x%p name is: %s and dentry = 0x%p",
+             inode, direntry->d_name.name, direntry);
+
+        tlink = cifs_sb_tlink(CIFS_SB(inode->i_sb));
+        rc = PTR_ERR(tlink);
+        if (IS_ERR(tlink))
+                goto free_xid;
+
+        rc = cifs_do_create(inode, direntry, xid, tlink, oflags, mode,
+                            &oplock, &fileHandle, &created);
+        if (!rc)
+                CIFSSMBClose(xid, tlink_tcon(tlink), fileHandle);
+
         cifs_put_tlink(tlink);
+free_xid:
         FreeXid(xid);
+
         return rc;
 }
 
@@ -492,16 +628,11 @@ cifs_lookup(struct inode *parent_dir_inode, struct dentry *direntry,
 {
         int xid;
         int rc = 0; /* to get around spurious gcc warning, set to zero here */
-        __u32 oplock;
-        __u16 fileHandle = 0;
-        bool posix_open = false;
         struct cifs_sb_info *cifs_sb;
         struct tcon_link *tlink;
         struct cifs_tcon *pTcon;
-        struct cifsFileInfo *cfile;
         struct inode *newInode = NULL;
         char *full_path = NULL;
-        struct file *filp;
 
         xid = GetXid();
 
@@ -518,31 +649,9 @@ cifs_lookup(struct inode *parent_dir_inode, struct dentry *direntry,
         }
         pTcon = tlink_tcon(tlink);
 
-        oplock = pTcon->ses->server->oplocks ? REQ_OPLOCK : 0;
-
-        /*
-         * Don't allow the separator character in a path component.
-         * The VFS will not allow "/", but "\" is allowed by posix.
-         */
-        if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_POSIX_PATHS)) {
-                int i;
-                for (i = 0; i < direntry->d_name.len; i++)
-                        if (direntry->d_name.name[i] == '\\') {
-                                cFYI(1, "Invalid file name");
-                                rc = -EINVAL;
-                                goto lookup_out;
-                        }
-        }
-
-        /*
-         * O_EXCL: optimize away the lookup, but don't hash the dentry. Let
-         * the VFS handle the create.
-         */
-        if (nd && (nd->flags & LOOKUP_EXCL)) {
-                d_instantiate(direntry, NULL);
-                rc = 0;
+        rc = check_name(direntry);
+        if (rc)
                 goto lookup_out;
-        }
 
         /* can not grab the rename sem here since it would
         deadlock in the cases (beginning of sys_rename itself)
@@ -560,80 +669,16 @@ cifs_lookup(struct inode *parent_dir_inode, struct dentry *direntry,
         }
         cFYI(1, "Full path: %s inode = 0x%p", full_path, direntry->d_inode);
 
-        /* Posix open is only called (at lookup time) for file create now.
-         * For opens (rather than creates), because we do not know if it
-         * is a file or directory yet, and current Samba no longer allows
-         * us to do posix open on dirs, we could end up wasting an open call
-         * on what turns out to be a dir. For file opens, we wait to call posix
-         * open till cifs_open.  It could be added here (lookup) in the future
-         * but the performance tradeoff of the extra network request when EISDIR
-         * or EACCES is returned would have to be weighed against the 50%
-         * reduction in network traffic in the other paths.
-         */
         if (pTcon->unix_ext) {
-                if (nd && !(nd->flags & LOOKUP_DIRECTORY) &&
-                     (nd->flags & LOOKUP_OPEN) && !pTcon->broken_posix_open &&
-                     (nd->intent.open.file->f_flags & O_CREAT)) {
-                        rc = cifs_posix_open(full_path, &newInode,
-                                        parent_dir_inode->i_sb,
-                                        nd->intent.open.create_mode,
-                                        nd->intent.open.file->f_flags, &oplock,
-                                        &fileHandle, xid);
-                        /*
-                         * The check below works around a bug in POSIX
-                         * open in samba versions 3.3.1 and earlier where
-                         * open could incorrectly fail with invalid parameter.
-                         * If either that or op not supported returned, follow
-                         * the normal lookup.
-                         */
-                        switch (rc) {
-                        case 0:
-                                /*
-                                 * The server may allow us to open things like
-                                 * FIFOs, but the client isn't set up to deal
-                                 * with that. If it's not a regular file, just
-                                 * close it and proceed as if it were a normal
-                                 * lookup.
-                                 */
-                                if (newInode && !S_ISREG(newInode->i_mode)) {
-                                        CIFSSMBClose(xid, pTcon, fileHandle);
-                                        break;
-                                }
-                        case -ENOENT:
-                                posix_open = true;
-                        case -EOPNOTSUPP:
-                                break;
-                        default:
-                                pTcon->broken_posix_open = true;
-                        }
-                }
-                if (!posix_open)
-                        rc = cifs_get_inode_info_unix(&newInode, full_path,
-                                                parent_dir_inode->i_sb, xid);
-        } else
+                rc = cifs_get_inode_info_unix(&newInode, full_path,
+                                              parent_dir_inode->i_sb, xid);
+        } else {
                 rc = cifs_get_inode_info(&newInode, full_path, NULL,
                                 parent_dir_inode->i_sb, xid, NULL);
+        }
 
         if ((rc == 0) && (newInode != NULL)) {
                 d_add(direntry, newInode);
-                if (posix_open) {
-                        filp = lookup_instantiate_filp(nd, direntry,
-                                                       generic_file_open);
-                        if (IS_ERR(filp)) {
-                                rc = PTR_ERR(filp);
-                                CIFSSMBClose(xid, pTcon, fileHandle);
-                                goto lookup_out;
-                        }
-
-                        cfile = cifs_new_fileinfo(fileHandle, filp, tlink,
-                                                  oplock);
-                        if (cfile == NULL) {
-                                fput(filp);
-                                CIFSSMBClose(xid, pTcon, fileHandle);
-                                rc = -ENOMEM;
-                                goto lookup_out;
-                        }
-                }
                 /* since paths are not looked up by component - the parent
                    directories are presumed to be good here */
                 renew_parental_timestamps(direntry);