I am Taniya Das and working in Linux Kernel internals, i just want to know " when i write to an open file(e.g abc.c) in Linux how does the Linux kernel interpret that write ".
Thanks
Taniya
taniyadas 0 Newbie Poster
jim mcnamara 19 Junior Poster
Interpreted?
write() calls are deferred to some future time by the kernel. However, any read() to that file after a write is guaranteed to be able to read the data written. This means that if the kernel panics just when a deferred write() call retruns, the data will be lost - i.e., not physically written to disk.
If a write cannot complete, it returns -1, and sets errno. If errno is set to EINTR, then the write can be re-tried. Most other errors indicate some kind of fatal condition. Always check the return code from a write.
If you need to guarantee that data is physically written to disk, there are the aio calls. Depending on your kernel release, these calls may not be implemented fully. With 2.6 I bleive they are now fully POSIX compliant. Try info aio or man aio_write
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