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| author | Maxim Devaev <mdevaev@gmail.com> | 2022-07-11 13:29:57 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-07-14 16:06:42 +0200 |
| commit | 421c8d9a20da92deed2dac227e7ebdee7eb3e88f (patch) | |
| tree | 9dd7b02019b4500836d798ac73042c36735cfe6f /drivers/usb/gadget/function/storage_common.c | |
| parent | 8097cf2fb3b2205257f1c76f4808e3398d66b6d9 (diff) | |
| download | linux-421c8d9a20da92deed2dac227e7ebdee7eb3e88f.tar.bz2 | |
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 'drivers/usb/gadget/function/storage_common.c')
| -rw-r--r-- | drivers/usb/gadget/function/storage_common.c | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/drivers/usb/gadget/function/storage_common.c b/drivers/usb/gadget/function/storage_common.c index b859a158a414..03035dbbe97b 100644 --- a/drivers/usb/gadget/function/storage_common.c +++ b/drivers/usb/gadget/function/storage_common.c @@ -519,4 +519,19 @@ ssize_t fsg_store_inquiry_string(struct fsg_lun *curlun, const char *buf, } EXPORT_SYMBOL_GPL(fsg_store_inquiry_string); +ssize_t fsg_store_forced_eject(struct fsg_lun *curlun, struct rw_semaphore *filesem, + const char *buf, size_t count) +{ + int ret; + + /* + * Forcibly detach the backing file from the LUN + * regardless of whether the host has allowed it. + */ + curlun->prevent_medium_removal = 0; + ret = fsg_store_file(curlun, filesem, "", 0); + return ret < 0 ? ret : count; +} +EXPORT_SYMBOL_GPL(fsg_store_forced_eject); + MODULE_LICENSE("GPL"); |