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authorMaxim Devaev <mdevaev@gmail.com>2022-07-11 13:29:57 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2022-07-14 17:06:42 +0300
commit421c8d9a20da92deed2dac227e7ebdee7eb3e88f (patch)
tree9dd7b02019b4500836d798ac73042c36735cfe6f /Documentation/usb/gadget-testing.rst
parent8097cf2fb3b2205257f1c76f4808e3398d66b6d9 (diff)
downloadlinux-421c8d9a20da92deed2dac227e7ebdee7eb3e88f.tar.xz
usb: gadget: f_mass_storage: forced_eject attribute
It allows to reset prevent_medium_removal flag and "eject" the image. This can be useful to free the drive from a hunging host or if the host continues to use the drive even after unmounting (Linux does this). It's also a bit like using an unfolded paperclip on an optical drive. Previously, the undocumented method of sending SIGUSR1 to a special "file-storage" kernel thread could be used for these purposes, but when using multiple storages there was no way to distinguish one from the other, so we had to send a signal to everyone. Reviewed-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Maxim Devaev <mdevaev@gmail.com> Link: https://lore.kernel.org/r/20220711102956.19642-1-mdevaev@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Documentation/usb/gadget-testing.rst')
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diff --git a/Documentation/usb/gadget-testing.rst b/Documentation/usb/gadget-testing.rst
index 1c37159fa171..2278c9ffb74a 100644
--- a/Documentation/usb/gadget-testing.rst
+++ b/Documentation/usb/gadget-testing.rst
@@ -333,6 +333,12 @@ In each lun directory there are the following attribute files:
being a CD-ROM.
nofua Flag specifying that FUA flag
in SCSI WRITE(10,12)
+ forced_eject This write-only file is useful only when
+ the function is active. It causes the backing
+ file to be forcibly detached from the LUN,
+ regardless of whether the host has allowed it.
+ Any non-zero number of bytes written will
+ result in ejection.
=============== ==============================================
Testing the MASS STORAGE function