Re: [PATCH 12/21] cifs: implement i_op->atomic_open()
From: Jeff Layton
Date: Mon Jul 02 2012 - 14:55:15 EST
On Tue, 5 Jun 2012 15:10:23 +0200
Miklos Szeredi <miklos@xxxxxxxxxx> wrote:
> From: Miklos Szeredi <mszeredi@xxxxxxx>
>
> 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@xxxxxxx>
> CC: Steve French <sfrench@xxxxxxxxx>
> ---
> fs/cifs/cifsfs.c | 1 +
> fs/cifs/cifsfs.h | 3 +
> fs/cifs/dir.c | 437 ++++++++++++++++++++++++++++++------------------------
> 3 files changed, 245 insertions(+), 196 deletions(-)
>
> diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
> index 8b6e344..dd29c7c 100644
> --- a/fs/cifs/cifsfs.c
> +++ b/fs/cifs/cifsfs.c
> @@ -778,6 +778,7 @@ struct file_system_type cifs_fs_type = {
> };
> const struct inode_operations cifs_dir_inode_ops = {
> .create = cifs_create,
> + .atomic_open = cifs_atomic_open,
> .lookup = cifs_lookup,
> .getattr = cifs_getattr,
> .unlink = cifs_unlink,
> diff --git a/fs/cifs/cifsfs.h b/fs/cifs/cifsfs.h
> index 6536535..3a572bf 100644
> --- a/fs/cifs/cifsfs.h
> +++ b/fs/cifs/cifsfs.h
> @@ -46,6 +46,9 @@ extern const struct inode_operations cifs_dir_inode_ops;
> extern struct inode *cifs_root_iget(struct super_block *);
> extern int cifs_create(struct inode *, struct dentry *, umode_t,
> struct nameidata *);
> +extern struct file *cifs_atomic_open(struct inode *, struct dentry *,
> + struct opendata *, unsigned, umode_t,
> + bool *);
> extern struct dentry *cifs_lookup(struct inode *, struct dentry *,
> struct nameidata *);
> extern int cifs_unlink(struct inode *dir, struct dentry *dentry);
> diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c
> index ec4e9a2..7a3dcd1 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 */
> + inode->i_sb, mode, oflags, oplock, fileHandle, xid);
> + switch (rc) {
> + case 0:
> + if (newinode == NULL) {
> + /* query inode info */
> + goto cifs_create_get_file_info;
> + }
>
> - if (rc == 0) {
> - if (newinode == NULL) /* query inode info */
> + 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;
> - 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) */
> - }
> + }
> + /* 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;
>
> - 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;
> + 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;
>
> - 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");
> + 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.
> + */
I wonder if we can't lift this condition now. We shouldn't do it in
this patch, but it's something we should experiment with after all of
this goes in.
> + 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;
Shouldn't we be basing these flags on the info in the nameidata -- at
least O_EXCL should depend on LOOKUP_EXCL, right? I see in Al's tree
that there's a follow-on patch that turns the create nameidata arg into
"bool excl". Seems like we should only be setting O_EXCL when that's
true.
Ugh, but that looks like an already existing bug...sigh...
I guess we can plan to fix that up after this goes in.
> + 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);
All in all, looks correct aside from the O_EXCL thing. I think we can
do some further cleanup here too, but I'd prefer to do that
incrementally on top of this rather than trying to do it all at once.
Nice work.
Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>
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