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author | Al Viro <viro@zeniv.linux.org.uk> | 2021-03-05 17:36:04 -0500 |
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committer | Steve French <stfrench@microsoft.com> | 2021-04-25 16:28:23 -0500 |
commit | f6a9bc336b600e1266e6eebb0972d75d5b93aea9 (patch) | |
tree | 62432d7b429006e2cdab9e9750565eec9e868fd9 /fs/cifs/smb2ops.c | |
parent | 8e33cf20ceb7f6d7a7e039f9f82a0cd1f3a6f964 (diff) | |
download | linux-f6a9bc336b600e1266e6eebb0972d75d5b93aea9.tar.bz2 |
cifs: allocate buffer in the caller of build_path_from_dentry()
build_path_from_dentry() open-codes dentry_path_raw(). The reason
we can't use dentry_path_raw() in there (and postprocess the
result as needed) is that the callers of build_path_from_dentry()
expect that the object to be freed on cleanup and the string to
be used are at the same address. That's painful, since the path
is naturally built end-to-beginning - we start at the leaf and
go through the ancestors, accumulating the pathname.
Life would be easier if we left the buffer allocation to callers.
It wouldn't be exact-sized buffer, but none of the callers keep
the result for long - it's always freed before the caller returns.
So there's no need to do exact-sized allocation; better use
__getname()/__putname(), same as we do for pathname arguments
of syscalls. What's more, there's no need to do allocation under
spinlocks, so GFP_ATOMIC is not needed.
Next patch will replace the open-coded dentry_path_raw() (in
build_path_from_dentry_optional_prefix()) with calling the real
thing. This patch only introduces wrappers for allocating/freeing
the buffers and switches to new calling conventions:
build_path_from_dentry(dentry, buf)
expects buf to be address of a page-sized object or NULL,
return value is a pathname built inside that buffer on success,
ERR_PTR(-ENOMEM) if buf is NULL and ERR_PTR(-ENAMETOOLONG) if
the pathname won't fit into page. Note that we don't need to
check for failure when allocating the buffer in the caller -
build_path_from_dentry() will do the right thing.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Steve French <stfrench@microsoft.com>
Diffstat (limited to 'fs/cifs/smb2ops.c')
-rw-r--r-- | fs/cifs/smb2ops.c | 17 |
1 files changed, 9 insertions, 8 deletions
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c index 30cfbebdd8b4..65fc65b26d84 100644 --- a/fs/cifs/smb2ops.c +++ b/fs/cifs/smb2ops.c @@ -2217,20 +2217,21 @@ smb3_notify(const unsigned int xid, struct file *pfile, struct smb3_notify notify; struct dentry *dentry = pfile->f_path.dentry; struct inode *inode = file_inode(pfile); - struct cifs_sb_info *cifs_sb; + struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb); struct cifs_open_parms oparms; struct cifs_fid fid; struct cifs_tcon *tcon; - const unsigned char *path = NULL; + const unsigned char *path; + void *page = alloc_dentry_path(); __le16 *utf16_path = NULL; u8 oplock = SMB2_OPLOCK_LEVEL_NONE; int rc = 0; - path = build_path_from_dentry(dentry); - if (path == NULL) - return -ENOMEM; - - cifs_sb = CIFS_SB(inode->i_sb); + path = build_path_from_dentry(dentry, page); + if (IS_ERR(path)) { + rc = PTR_ERR(path); + goto notify_exit; + } utf16_path = cifs_convert_path_to_utf16(path + 1, cifs_sb); if (utf16_path == NULL) { @@ -2264,7 +2265,7 @@ smb3_notify(const unsigned int xid, struct file *pfile, cifs_dbg(FYI, "change notify for path %s rc %d\n", path, rc); notify_exit: - kfree(path); + free_dentry_path(page); kfree(utf16_path); return rc; } |