Messages in this thread | | | From | Joerg Schilling <> | Date | Mon, 13 Feb 2006 11:30:10 +0100 | Subject | Re: CD writing in future Linux (stirring up a hornets' nest) |
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"Christopher Friesen" <cfriesen@nortel.com> wrote:
> Joerg Schilling wrote: > > "Christopher Friesen" <cfriesen@nortel.com> wrote: > > >>There's nothing there that says the mapping cannot change with > >>time...just that it has to be unique. > > > > > > If it changes over the runtime of a program, it is not unique from the > > view of that program. > > That depends on what "uniquely identified" actually means. > > One possible definition is that at any time, a particular path maps to a > single unique st_ino/st_dev tuple. > > The other possibility (and this is what you seem to be advocating) is > that a st_ino/st_dev tuple always maps to the same file over the entire > runtime of the system.
Well it is obvious that this is a requirement.
If Linux does device name mapping at high level but leaves the low level part unstable, then the following coul happen:
Just think about a program that checks a file that is on a removable media.
This media is mounted via a vold service and someone removes the USB cable and reinserts it a second later. The filesystem on the device will be mounted on the same mount point but the device ID inside the system did change.
As a result, the file unique identification st_ino/st_dev is not retained and the program is confused.
Jörg
-- EMail:joerg@schily.isdn.cs.tu-berlin.de (home) Jörg Schilling D-13353 Berlin js@cs.tu-berlin.de (uni) schilling@fokus.fraunhofer.de (work) Blog: http://schily.blogspot.com/ URL: http://cdrecord.berlios.de/old/private/ ftp://ftp.berlios.de/pub/schily - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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