Commit 55aa601e authored by Phillip Susi's avatar Phillip Susi Committed by Linus Torvalds
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[PATCH] Update udf documentation to reflect current state of read/write support

Change Documentation/filesystems/udf.txt from saying that read/write mounts
on cd media are not supported to instead state the current level of
support.  Specifically that it works fine on dvd+rw media and can be made
to work on cd-rw media via the pktcdvd device.

Cc: Peter Osterlund <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent d6ddf554
......@@ -7,8 +7,17 @@ If you encounter problems with reading UDF discs using this driver,
please report them to, which is the
developer's list.
Write support requires a block driver which supports writing. The current
scsi and ide cdrom drivers do not support writing.
Write support requires a block driver which supports writing. Currently
dvd+rw drives and media support true random sector writes, and so a udf
filesystem on such devices can be directly mounted read/write. CD-RW
media however, does not support this. Instead the media can be formatted
for packet mode using the utility cdrwtool, then the pktcdvd driver can
be bound to the underlying cd device to provide the required buffering
and read-modify-write cycles to allow the filesystem random sector writes
while providing the hardware with only full packet writes. While not
required for dvd+rw media, use of the pktcdvd driver often enhances
performance due to very poor read-modify-write support supplied internally
by drive firmware.
The following mount options are supported:
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