I tried to write to a file on a read-only mounted nfs file system. The
write system call returns a value depending on whether the O_SYNC flag was
set during the open system call.
If O_SYNC flag is set, the nfs_updatepage() function returns "Read Only
file system" error but if O_SYNC flag is not set the nfs_updatepage()
returns the count itself. This error is subsequently returned by the write
system call.
Can someone help me out with following doubts :
1. If O_SYNC flag is not set then does the kernel caches the write
request? What happens in the NFS V2 protocol (as far as i remember in V2
protocol clients do not cache write requests) ?
2. Has POSIX defined some standard for behaviour of read/write system
calls for an NFS file (or any other standard/rfc in use)?
3. This behaviour does no seem to be correct because if an application has
not set the O_SYNC flag and tries (unknowingly) to write to a Read Only
NFS file then it will never know that an error occured?
Thanks,
Sushil.
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