Messages in this thread | | | Date | Sun, 24 Jun 2001 23:01:23 -0400 | From | (Ho Chak Hung) | Subject | Re: How does ramfs actually fills the page cache with data? |
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thanks a lot for your reply
But is it at all possible to put data into page cache without going through the inodes or files? I mean, for example, if you are given a string "abcde", and you want to allocate a page to store this "abcde" into that page and add that page to the page cache, what would you do?
2)The ramfs uses the generic file operation Ingo Oeser <ingo.oeser@informatik.tu-chemnitz.de> wrote: > > On Fri, Jun 22, 2001 at 05:45:27PM -0400, Ho Chak Hung wrote: > > In fs/ramfs/inode.c, how does ramfs actually fills the page > > cache with data? In the readpage operation, it only zero-fill > > the page if it didn't already exist in the page cache. However, > > how do I actually fill the page with data? > > The page cache does it itself. > > "readpage" is to move pages from the backing store into the page > cache. > > "writepage" and friends is for updating the backing store with > the contents of the page cache. > > There is no real backing store of ramfs, since ramfs data lives > completly in page cache. > > But we cannot give the user random memory contents, so we zero it > out on readpage and prepare_write. > > The data is copied with copy_{from,to}_user in the generic file > operations (look how ramfs_file_operations is defined and look at > the functions referenced), which read/write through page cache. > > Regards > > Ingo Oeser > -- > Use ReiserFS to get a faster fsck and Ext2 to fsck slowly and gently. > - > 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/ > __________________________________________________________________ __________________________________________________________________ Get your own FREE, personal Netscape Webmail account today at http://webmail.netscape.com/ - 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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