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Commit ca0daa27 authored by Trond Myklebust's avatar Trond Myklebust
Browse files

NFS: Cache aggressively when file is open for writing 



Unless the user is using file locking, we must assume close-to-open
cache consistency when the file is open for writing. Adjust the
caching algorithm so that it does not clear the cache on out-of-order
writes and/or attribute revalidations.

Signed-off-by: default avatarTrond Myklebust <trond.myklebust@primarydata.com>
parent 57b69181

fs/nfs/file.c

+2 −11
Original line number Diff line number Diff line
@@ -779,11 +779,6 @@ do_unlk(struct file *filp, int cmd, struct file_lock *fl, int is_local) 
	return status;

}



static int

is_time_granular(struct timespec *ts) {

	return ((ts->tv_sec == 0) && (ts->tv_nsec <= 1000));

}



static int

do_setlk(struct file *filp, int cmd, struct file_lock *fl, int is_local)

{
@@ -817,12 +812,8 @@ do_setlk(struct file *filp, int cmd, struct file_lock *fl, int is_local) 
	 * This makes locking act as a cache coherency point.

	 */

	nfs_sync_mapping(filp->f_mapping);

	if (!NFS_PROTO(inode)->have_delegation(inode, FMODE_READ)) {

		if (is_time_granular(&NFS_SERVER(inode)->time_delta))

			__nfs_revalidate_inode(NFS_SERVER(inode), inode);

		else

			nfs_zap_caches(inode);

	}

	if (!NFS_PROTO(inode)->have_delegation(inode, FMODE_READ))

		nfs_zap_mapping(inode, filp->f_mapping);

out:

	return status;

}

fs/nfs/inode.c

+44 −18
Original line number Diff line number Diff line
@@ -878,7 +878,10 @@ void nfs_inode_attach_open_context(struct nfs_open_context *ctx) 
	struct nfs_inode *nfsi = NFS_I(inode);



	spin_lock(&inode->i_lock);

	if (ctx->mode & FMODE_WRITE)

		list_add(&ctx->list, &nfsi->open_files);

	else

		list_add_tail(&ctx->list, &nfsi->open_files);

	spin_unlock(&inode->i_lock);

}

EXPORT_SYMBOL_GPL(nfs_inode_attach_open_context);
@@ -1215,6 +1218,25 @@ int nfs_revalidate_mapping_protected(struct inode *inode, struct address_space * 
	return __nfs_revalidate_mapping(inode, mapping, true);

}



static bool nfs_file_has_writers(struct nfs_inode *nfsi)

{

	struct inode *inode = &nfsi->vfs_inode;



	assert_spin_locked(&inode->i_lock);



	if (!S_ISREG(inode->i_mode))

		return false;

	if (list_empty(&nfsi->open_files))

		return false;

	/* Note: This relies on nfsi->open_files being ordered with writers

	 *       being placed at the head of the list.

	 *       See nfs_inode_attach_open_context()

	 */

	return (list_first_entry(&nfsi->open_files,

			struct nfs_open_context,

			list)->mode & FMODE_WRITE) == FMODE_WRITE;

}



static unsigned long nfs_wcc_update_inode(struct inode *inode, struct nfs_fattr *fattr)

{

	struct nfs_inode *nfsi = NFS_I(inode);
@@ -1279,22 +1301,24 @@ static int nfs_check_inode_attributes(struct inode *inode, struct nfs_fattr *fat 
	if ((fattr->valid & NFS_ATTR_FATTR_TYPE) && (inode->i_mode & S_IFMT) != (fattr->mode & S_IFMT))

		return -EIO;



	if ((fattr->valid & NFS_ATTR_FATTR_CHANGE) != 0 &&

			inode->i_version != fattr->change_attr)

	if (!nfs_file_has_writers(nfsi)) {

		/* Verify a few of the more important attributes */

		if ((fattr->valid & NFS_ATTR_FATTR_CHANGE) != 0 && inode->i_version != fattr->change_attr)

			invalid |= NFS_INO_INVALID_ATTR | NFS_INO_REVAL_PAGECACHE;



	/* Verify a few of the more important attributes */

		if ((fattr->valid & NFS_ATTR_FATTR_MTIME) && !timespec_equal(&inode->i_mtime, &fattr->mtime))

			invalid |= NFS_INO_INVALID_ATTR;



		if ((fattr->valid & NFS_ATTR_FATTR_CTIME) && !timespec_equal(&inode->i_ctime, &fattr->ctime))

			invalid |= NFS_INO_INVALID_ATTR;



		if (fattr->valid & NFS_ATTR_FATTR_SIZE) {

			cur_size = i_size_read(inode);

			new_isize = nfs_size_to_loff_t(fattr->size);

			if (cur_size != new_isize)

				invalid |= NFS_INO_INVALID_ATTR|NFS_INO_REVAL_PAGECACHE;

		}

	if (nfsi->nrequests != 0)

		invalid &= ~NFS_INO_REVAL_PAGECACHE;

	}



	/* Have any file permissions changed? */

	if ((fattr->valid & NFS_ATTR_FATTR_MODE) && (inode->i_mode & S_IALLUGO) != (fattr->mode & S_IALLUGO))
@@ -1526,7 +1550,7 @@ EXPORT_SYMBOL_GPL(nfs_refresh_inode); 


static int nfs_post_op_update_inode_locked(struct inode *inode, struct nfs_fattr *fattr)

{

	unsigned long invalid = NFS_INO_INVALID_ATTR|NFS_INO_REVAL_PAGECACHE;

	unsigned long invalid = NFS_INO_INVALID_ATTR;



	/*

	 * Don't revalidate the pagecache if we hold a delegation, but do
@@ -1675,6 +1699,7 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr) 
	unsigned long invalid = 0;

	unsigned long now = jiffies;

	unsigned long save_cache_validity;

	bool have_writers = nfs_file_has_writers(nfsi);

	bool cache_revalidated = true;



	dfprintk(VFS, "NFS: %s(%s/%lu fh_crc=0x%08x ct=%d info=0x%x)\n",
@@ -1730,7 +1755,7 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr) 
			dprintk("NFS: change_attr change on server for file %s/%ld\n",

					inode->i_sb->s_id, inode->i_ino);

			/* Could it be a race with writeback? */

			if (nfsi->nrequests == 0) {

			if (!have_writers) {

				invalid |= NFS_INO_INVALID_ATTR

					| NFS_INO_INVALID_DATA

					| NFS_INO_INVALID_ACCESS
@@ -1770,8 +1795,9 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr) 
		if (new_isize != cur_isize) {

			/* Do we perhaps have any outstanding writes, or has

			 * the file grown beyond our last write? */

			if ((nfsi->nrequests == 0) || new_isize > cur_isize) {

			if (nfsi->nrequests == 0 || new_isize > cur_isize) {

				i_size_write(inode, new_isize);

				if (!have_writers)

					invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA;

			}

			dprintk("NFS: isize change on server for file %s/%ld "