Add passphrase_file to mount options (refactored)

bcachefs.8

@@ -380,6 +380,12 @@ is the path where the filesystem should be mounted. If not set, then the filesys
 but all steps preceding mounting the filesystem (e.g. asking for passphrase) will still be performed.
 .Pp the options are as follows:
 .Bl -tag -width Ds
+.It Fl f , Fl -passphrase-file Ns = Ns Ar passphrase_file
+Path to passphrase/key file
+.sp
+Precedes key_location/unlock_policy: if the filesystem can be decrypted by the specified passphrase
+file, it is decrypted. (i.e. Regardless if "fail" is specified for key_location/unlock_policy.)
+.El
 .It Fl o Ar options
 Mount options provided as a comma-separated list. See user guide for complete list.
 .Bl -tag -width Ds -compact
@@ -393,6 +399,8 @@ Run fsck during mount
 Fix errors without asking during fsck
 .It Cm read_only
 Mount in read only mode
+.It Cm passphrase_file Ns = Ns Ar passphrase_file
+Path to passphrase/key file
 .It Cm version_upgrade
 .El
 .It Fl k , Fl -key-location Ns = Ns ( Cm fail | wait | ask )
@@ -408,6 +416,7 @@ prompt the user for password.
 .El
 .It Fl c , Fl -colorize Ns = Ns ( Cm true | false )
 Force color on/off. Default: auto-detect TTY
+.El
 .It Fl v
 Be verbose. Can be specified more than once.
 .El

src/commands/mount.rs

@@ -305,6 +305,18 @@ fn devs_str_sbs_from_device(
     }
 }
 
+fn parse_passphrase_file_from_mount_options(options: impl AsRef<str>) -> Option<PathBuf> {
+    options
+        .as_ref()
+        .split(',')
+        .fold(None, |_, next| match next {
+            x if x.starts_with("passphrase_file") => {
+                Some(PathBuf::from(x.split('=').nth(1).unwrap().to_string()))
+            }
+            _ => None,
+        })
+}
+
 fn cmd_mount_inner(opt: Cli) -> Result<()> {
     // Grab the udev information once
     let udev_info = udev_bcachefs_info()?;
@@ -338,18 +350,12 @@ fn cmd_mount_inner(opt: Cli) -> Result<()> {
 
     if unsafe { bcachefs::bch2_sb_is_encrypted(first_sb.sb) } {
         let _key_handle: KeyHandle = KeyHandle::new_from_search(&uuid).or_else(|_| {
-            opt.passphrase_file
-                .and_then(|path| match Passphrase::new_from_file(&first_sb, path) {
-                    Ok(p) => Some(KeyHandle::new(&first_sb, &p)),
-                    Err(e) => {
-                        error!(
-                            "Failed to read passphrase from file, falling back to prompt: {}",
-                            e
-                        );
-                        None
-                    }
-                })
-                .unwrap_or_else(|| opt.unlock_policy.apply(&first_sb))
+            attempt_unlock_master_key(
+                opt.passphrase_file,
+                &opt.options,
+                opt.unlock_policy,
+                first_sb,
+            )
         })?;
     }
 
@@ -373,6 +379,48 @@ fn cmd_mount_inner(opt: Cli) -> Result<()> {
     }
 }
 
+fn attempt_unlock_master_key(
+    passphrase_file: Option<PathBuf>,
+    options: &String,
+    unlock_policy: UnlockPolicy,
+    first_sb: bch_sb_handle,
+) -> Result<KeyHandle, anyhow::Error> {
+    // Unlock by key_file CLI option
+    passphrase_file
+        .and_then(
+            |path| match Passphrase::new_from_file(&first_sb, path.clone()) {
+                Ok(p) => Some(KeyHandle::new(&first_sb, &p)),
+                Err(e) => {
+                    error!(
+                        "Failed to read passphrase from path \"{}\". Error: {}",
+                        path.display(),
+                        e
+                    );
+                    None
+                }
+            },
+        )
+        // Unlock by key_file mount option
+        .unwrap_or_else(|| {
+            parse_passphrase_file_from_mount_options(options)
+                .and_then(|path: PathBuf| {
+                    match Passphrase::new_from_file(&first_sb, path.clone()) {
+                        Ok(p) => Some(KeyHandle::new(&first_sb, &p)),
+                        Err(e) => {
+                            error!(
+                                "Failed to read passphrase from path \"{}\". Error: {}",
+                                path.display(),
+                                e
+                            );
+                            None
+                        }
+                    }
+                })
+                // Unlock by unlock policy
+                .unwrap_or_else(|| unlock_policy.apply(&first_sb))
+        })
+}
+
 pub fn mount(mut argv: Vec<String>, symlink_cmd: Option<&str>) -> i32 {
     // If the bcachefs tool is being called as "bcachefs mount dev ..." (as opposed to via a
     // symlink like "/usr/sbin/mount.bcachefs dev ...", then we need to pop the 0th argument