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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/file.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/file.c')
-rw-r--r-- | fs/cifs/file.c | 75 |
1 files changed, 36 insertions, 39 deletions
diff --git a/fs/cifs/file.c b/fs/cifs/file.c index af49b3937e15..3d4e6e7dac1d 100644 --- a/fs/cifs/file.c +++ b/fs/cifs/file.c @@ -530,7 +530,8 @@ int cifs_open(struct inode *inode, struct file *file) struct cifs_tcon *tcon; struct tcon_link *tlink; struct cifsFileInfo *cfile = NULL; - const char *full_path = NULL; + void *page; + const char *full_path; bool posix_open_ok = false; struct cifs_fid fid; struct cifs_pending_open open; @@ -546,9 +547,10 @@ int cifs_open(struct inode *inode, struct file *file) tcon = tlink_tcon(tlink); server = tcon->ses->server; - full_path = build_path_from_dentry(file_dentry(file)); - if (full_path == NULL) { - rc = -ENOMEM; + page = alloc_dentry_path(); + full_path = build_path_from_dentry(file_dentry(file), page); + if (IS_ERR(full_path)) { + rc = PTR_ERR(full_path); goto out; } @@ -640,7 +642,7 @@ int cifs_open(struct inode *inode, struct file *file) } out: - kfree(full_path); + free_dentry_path(page); free_xid(xid); cifs_put_tlink(tlink); return rc; @@ -689,7 +691,8 @@ cifs_reopen_file(struct cifsFileInfo *cfile, bool can_flush) struct TCP_Server_Info *server; struct cifsInodeInfo *cinode; struct inode *inode; - const char *full_path = NULL; + void *page; + const char *full_path; int desired_access; int disposition = FILE_OPEN; int create_options = CREATE_NOT_DIR; @@ -699,9 +702,8 @@ cifs_reopen_file(struct cifsFileInfo *cfile, bool can_flush) mutex_lock(&cfile->fh_mutex); if (!cfile->invalidHandle) { mutex_unlock(&cfile->fh_mutex); - rc = 0; free_xid(xid); - return rc; + return 0; } inode = d_inode(cfile->dentry); @@ -715,12 +717,13 @@ cifs_reopen_file(struct cifsFileInfo *cfile, bool can_flush) * called and if the server was down that means we end up here, and we * can never tell if the caller already has the rename_sem. */ - full_path = build_path_from_dentry(cfile->dentry); - if (full_path == NULL) { - rc = -ENOMEM; + page = alloc_dentry_path(); + full_path = build_path_from_dentry(cfile->dentry, page); + if (IS_ERR(full_path)) { mutex_unlock(&cfile->fh_mutex); + free_dentry_path(page); free_xid(xid); - return rc; + return PTR_ERR(full_path); } cifs_dbg(FYI, "inode = 0x%p file flags 0x%x for %s\n", @@ -838,7 +841,7 @@ reopen_success: cifs_relock_file(cfile); reopen_error_exit: - kfree(full_path); + free_dentry_path(page); free_xid(xid); return rc; } @@ -2069,34 +2072,31 @@ cifs_get_writable_path(struct cifs_tcon *tcon, const char *name, int flags, struct cifsFileInfo **ret_file) { - struct list_head *tmp; struct cifsFileInfo *cfile; - struct cifsInodeInfo *cinode; - const char *full_path; + void *page = alloc_dentry_path(); *ret_file = NULL; spin_lock(&tcon->open_file_lock); - list_for_each(tmp, &tcon->openFileList) { - cfile = list_entry(tmp, struct cifsFileInfo, - tlist); - full_path = build_path_from_dentry(cfile->dentry); - if (full_path == NULL) { + list_for_each_entry(cfile, &tcon->openFileList, tlist) { + struct cifsInodeInfo *cinode; + const char *full_path = build_path_from_dentry(cfile->dentry, page); + if (IS_ERR(full_path)) { spin_unlock(&tcon->open_file_lock); - return -ENOMEM; + free_dentry_path(page); + return PTR_ERR(full_path); } - if (strcmp(full_path, name)) { - kfree(full_path); + if (strcmp(full_path, name)) continue; - } - kfree(full_path); cinode = CIFS_I(d_inode(cfile->dentry)); spin_unlock(&tcon->open_file_lock); + free_dentry_path(page); return cifs_get_writable_file(cinode, flags, ret_file); } spin_unlock(&tcon->open_file_lock); + free_dentry_path(page); return -ENOENT; } @@ -2104,35 +2104,32 @@ int cifs_get_readable_path(struct cifs_tcon *tcon, const char *name, struct cifsFileInfo **ret_file) { - struct list_head *tmp; struct cifsFileInfo *cfile; - struct cifsInodeInfo *cinode; - const char *full_path; + void *page = alloc_dentry_path(); *ret_file = NULL; spin_lock(&tcon->open_file_lock); - list_for_each(tmp, &tcon->openFileList) { - cfile = list_entry(tmp, struct cifsFileInfo, - tlist); - full_path = build_path_from_dentry(cfile->dentry); - if (full_path == NULL) { + list_for_each_entry(cfile, &tcon->openFileList, tlist) { + struct cifsInodeInfo *cinode; + const char *full_path = build_path_from_dentry(cfile->dentry, page); + if (IS_ERR(full_path)) { spin_unlock(&tcon->open_file_lock); - return -ENOMEM; + free_dentry_path(page); + return PTR_ERR(full_path); } - if (strcmp(full_path, name)) { - kfree(full_path); + if (strcmp(full_path, name)) continue; - } - kfree(full_path); cinode = CIFS_I(d_inode(cfile->dentry)); spin_unlock(&tcon->open_file_lock); + free_dentry_path(page); *ret_file = find_readable_file(cinode, 0); return *ret_file ? 0 : -ENOENT; } spin_unlock(&tcon->open_file_lock); + free_dentry_path(page); return -ENOENT; } |