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smb3: do not error on fsync when readonly

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[ Upstream commit 71e6864eacbef0b2645ca043cdfbac272cb6cea3 ]

Linux allows doing a flush/fsync on a file open for read-only,
but the protocol does not allow that.  If the file passed in
on the flush is read-only try to find a writeable handle for
the same inode, if that is not possible skip sending the
fsync call to the server to avoid breaking the apps.

Reported-by: Julian Sikorski <belegdol@gmail.com>
Tested-by: Julian Sikorski <belegdol@gmail.com>
Suggested-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Steve French 2021-11-10 01:47:48 -06:00 committed by Greg Kroah-Hartman
parent c380062d08
commit 5655b8bccb
1 changed files with 29 additions and 6 deletions
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35
fs/cifs/file.c
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@ -2618,12 +2618,23 @@ int cifs_strict_fsync(struct file *file, loff_t start, loff_t end,
tcon = tlink_tcon(smbfile->tlink);
if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOSSYNC)) {
server = tcon->ses->server;
if (server->ops->flush)
rc = server->ops->flush(xid, tcon, &smbfile->fid);
else
if (server->ops->flush == NULL) {
rc = -ENOSYS;
goto strict_fsync_exit;
}
if ((OPEN_FMODE(smbfile->f_flags) & FMODE_WRITE) == 0) {
smbfile = find_writable_file(CIFS_I(inode), FIND_WR_ANY);
if (smbfile) {
rc = server->ops->flush(xid, tcon, &smbfile->fid);
cifsFileInfo_put(smbfile);
} else
cifs_dbg(FYI, "ignore fsync for file not open for write\n");
} else
rc = server->ops->flush(xid, tcon, &smbfile->fid);
}
strict_fsync_exit:
free_xid(xid);
return rc;
}
@ -2635,6 +2646,7 @@ int cifs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
struct cifs_tcon *tcon;
struct TCP_Server_Info *server;
struct cifsFileInfo *smbfile = file->private_data;
struct inode *inode = file_inode(file);
struct cifs_sb_info *cifs_sb = CIFS_FILE_SB(file);
rc = file_write_and_wait_range(file, start, end);
@ -2651,12 +2663,23 @@ int cifs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
tcon = tlink_tcon(smbfile->tlink);
if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOSSYNC)) {
server = tcon->ses->server;
if (server->ops->flush)
rc = server->ops->flush(xid, tcon, &smbfile->fid);
else
if (server->ops->flush == NULL) {
rc = -ENOSYS;
goto fsync_exit;
}
if ((OPEN_FMODE(smbfile->f_flags) & FMODE_WRITE) == 0) {
smbfile = find_writable_file(CIFS_I(inode), FIND_WR_ANY);
if (smbfile) {
rc = server->ops->flush(xid, tcon, &smbfile->fid);
cifsFileInfo_put(smbfile);
} else
cifs_dbg(FYI, "ignore fsync for file not open for write\n");
} else
rc = server->ops->flush(xid, tcon, &smbfile->fid);
}
fsync_exit:
free_xid(xid);
return rc;
}