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NFS: Instrument i_size_write()

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Generate a trace event whenever the NFS client modifies the size of
a file. These new events aid troubleshooting workloads that trigger
races around size updates.

There are four new trace points, all named nfs_size_something so
they are easy to grep for or enable as a group with a single glob.

Size updated on the server:

  kworker/u24:10-194   [010]   369.939174: nfs_size_update:      fileid=00:28:2 fhandle=0x36fbbe51 version=1752899344277980615 cursize=250471 newsize=172083

Server-side size update reported via NFSv3 WCC attributes:

             fsx-1387  [006]   380.760686: nfs_size_wcc:         fileid=00:28:2 fhandle=0x36fbbe51 version=1752899355909932456 cursize=146792 newsize=171216

File has been truncated locally:

             fsx-1387  [007]   369.437421: nfs_size_truncate:    fileid=00:28:2 fhandle=0x36fbbe51 version=1752899231200117272 cursize=215244 newsize=0

File has been extended locally:

             fsx-1387  [007]   369.439213: nfs_size_grow:        fileid=00:28:2 fhandle=0x36fbbe51 version=1752899343704248410 cursize=258048 newsize=262144

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
This commit is contained in:
Chuck Lever 2021-10-04 10:10:16 -04:00 committed by Trond Myklebust
parent 0392dd51f9
commit 110cb2d2f9
3 changed files with 54 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
fs/nfs/inode.c
View File

@ -671,6 +671,7 @@ static int nfs_vmtruncate(struct inode * inode, loff_t offset)
if (err)
goto out;
trace_nfs_size_truncate(inode, offset);
i_size_write(inode, offset);
/* Optimisation */
if (offset == 0)
@ -1456,6 +1457,7 @@ static void nfs_wcc_update_inode(struct inode *inode, struct nfs_fattr *fattr)
&& (fattr->valid & NFS_ATTR_FATTR_SIZE)
&& i_size_read(inode) == nfs_size_to_loff_t(fattr->pre_size)
&& !nfs_have_writebacks(inode)) {
trace_nfs_size_wcc(inode, fattr->size);
i_size_write(inode, nfs_size_to_loff_t(fattr->size));
}
}
@ -2100,16 +2102,11 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr)
/* Do we perhaps have any outstanding writes, or has
* the file grown beyond our last write? */
if (!nfs_have_writebacks(inode) || new_isize > cur_isize) {
trace_nfs_size_update(inode, new_isize);
i_size_write(inode, new_isize);
if (!have_writers)
invalid |= NFS_INO_INVALID_DATA;
}
dprintk("NFS: isize change on server for file %s/%ld "
"(%Ld to %Ld)\n",
inode->i_sb->s_id,
inode->i_ino,
(long long)cur_isize,
(long long)new_isize);
}
if (new_isize == 0 &&
!(fattr->valid & (NFS_ATTR_FATTR_SPACE_USED |

50
fs/nfs/nfstrace.h
View File

@ -231,6 +231,56 @@ TRACE_EVENT(nfs_access_exit,
)
);
DECLARE_EVENT_CLASS(nfs_update_size_class,
TP_PROTO(
const struct inode *inode,
loff_t new_size
),
TP_ARGS(inode, new_size),
TP_STRUCT__entry(
__field(dev_t, dev)
__field(u32, fhandle)
__field(u64, fileid)
__field(u64, version)
__field(loff_t, cur_size)
__field(loff_t, new_size)
),
TP_fast_assign(
const struct nfs_inode *nfsi = NFS_I(inode);
__entry->dev = inode->i_sb->s_dev;
__entry->fhandle = nfs_fhandle_hash(&nfsi->fh);
__entry->fileid = nfsi->fileid;
__entry->version = inode_peek_iversion_raw(inode);
__entry->cur_size = i_size_read(inode);
__entry->new_size = new_size;
),
TP_printk(
"fileid=%02x:%02x:%llu fhandle=0x%08x version=%llu cursize=%lld newsize=%lld",
MAJOR(__entry->dev), MINOR(__entry->dev),
(unsigned long long)__entry->fileid,
__entry->fhandle, __entry->version,
__entry->cur_size, __entry->new_size
)
);
#define DEFINE_NFS_UPDATE_SIZE_EVENT(name) \
DEFINE_EVENT(nfs_update_size_class, nfs_size_##name, \
TP_PROTO( \
const struct inode *inode, \
loff_t new_size \
), \
TP_ARGS(inode, new_size))
DEFINE_NFS_UPDATE_SIZE_EVENT(truncate);
DEFINE_NFS_UPDATE_SIZE_EVENT(wcc);
DEFINE_NFS_UPDATE_SIZE_EVENT(update);
DEFINE_NFS_UPDATE_SIZE_EVENT(grow);
#define show_lookup_flags(flags) \
__print_flags(flags, "|", \
{ LOOKUP_FOLLOW, "FOLLOW" }, \

1
fs/nfs/write.c
View File

@ -288,6 +288,7 @@ static void nfs_grow_file(struct page *page, unsigned int offset, unsigned int c
end = page_file_offset(page) + ((loff_t)offset+count);
if (i_size >= end)
goto out;
trace_nfs_size_grow(inode, end);
i_size_write(inode, end);
NFS_I(inode)->cache_validity &= ~NFS_INO_INVALID_SIZE;
nfs_inc_stats(inode, NFSIOS_EXTENDWRITE);