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NFS: Cache aggressively when file is open for writing
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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: Trond Myklebust <trond.myklebust@primarydata.com>
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Trond Myklebust committed Jun 22, 2016
1 parent 57b6918 commit ca0daa2
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Showing 2 changed files with 46 additions and 29 deletions.
13 changes: 2 additions & 11 deletions fs/nfs/file.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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)
{
Expand Down Expand Up @@ -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;
}
Expand Down
62 changes: 44 additions & 18 deletions fs/nfs/inode.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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);
list_add(&ctx->list, &nfsi->open_files);
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);
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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)
invalid |= NFS_INO_INVALID_ATTR|NFS_INO_REVAL_PAGECACHE;
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_MTIME) && !timespec_equal(&inode->i_mtime, &fattr->mtime))
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 ((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))
Expand Down Expand Up @@ -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
Expand Down Expand Up @@ -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",
Expand Down Expand Up @@ -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
Expand Down Expand Up @@ -1770,9 +1795,10 @@ 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);
invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA;
if (!have_writers)
invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA;
}
dprintk("NFS: isize change on server for file %s/%ld "
"(%Ld to %Ld)\n",
Expand Down

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