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72cb77f4a5
linux/fs/nfs/internal.h
Trond Myklebust 72cb77f4a5 NFS: Throttle page dirtying while we're flushing to disk 
The following patch is a combination of a patch by myself and Peter
Staubach.

Trond: If we allow other processes to dirty pages while a process is doing
a consistency sync to disk, we can end up never making progress.

Peter: Attached is a patch which addresses a continuing problem with
the NFS client generating out of order WRITE requests.  While
this is compliant with all of the current protocol
specifications, there are servers in the market which can not
handle out of order WRITE requests very well.  Also, this may
lead to sub-optimal block allocations in the underlying file
system on the server.  This may cause the read throughputs to
be reduced when reading the file from the server.

Peter: There has been a lot of work recently done to address out of
order issues on a systemic level.  However, the NFS client is
still susceptible to the problem.  Out of order WRITE
requests can occur when pdflush is in the middle of writing
out pages while the process dirtying the pages calls
generic_file_buffered_write which calls
generic_perform_write which calls
balance_dirty_pages_rate_limited which ends up calling
writeback_inodes which ends up calling back into the NFS
client to writes out dirty pages for the same file that
pdflush happens to be working with.

Signed-off-by: Peter Staubach <staubach@redhat.com>
[modification by Trond to merge the two similar patches]
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2009-03-11 14:10:30 -04:00

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/*
* NFS internal definitions
*/
#include <linux/mount.h>
#include <linux/security.h>
struct nfs_string;
/* Maximum number of readahead requests
* FIXME: this should really be a sysctl so that users may tune it to suit
* their needs. People that do NFS over a slow network, might for
* instance want to reduce it to something closer to 1 for improved
* interactive response.
*/
#define NFS_MAX_READAHEAD (RPC_DEF_SLOT_TABLE - 1)
struct nfs_clone_mount {
const struct super_block *sb;
const struct dentry *dentry;
struct nfs_fh *fh;
struct nfs_fattr *fattr;
char *hostname;
char *mnt_path;
struct sockaddr *addr;
size_t addrlen;
rpc_authflavor_t authflavor;
};
/*
* In-kernel mount arguments
*/
struct nfs_parsed_mount_data {
int flags;
int rsize, wsize;
int timeo, retrans;
int acregmin, acregmax,
acdirmin, acdirmax;
int namlen;
unsigned int bsize;
unsigned int auth_flavor_len;
rpc_authflavor_t auth_flavors[1];
char *client_address;
struct {
struct sockaddr_storage address;
size_t addrlen;
char *hostname;
u32 version;
unsigned short port;
unsigned short protocol;
} mount_server;
struct {
struct sockaddr_storage address;
size_t addrlen;
char *hostname;
char *export_path;
unsigned short port;
unsigned short protocol;
} nfs_server;
struct security_mnt_opts lsm_opts;
};
/* mount_clnt.c */
struct nfs_mount_request {
struct sockaddr *sap;
size_t salen;
char *hostname;
char *dirpath;
u32 version;
unsigned short protocol;
struct nfs_fh *fh;
int noresvport;
};
extern int nfs_mount(struct nfs_mount_request *info);
/* client.c */
extern struct rpc_program nfs_program;
extern void nfs_put_client(struct nfs_client *);
extern struct nfs_client *nfs_find_client(const struct sockaddr *, u32);
extern struct nfs_client *nfs_find_client_next(struct nfs_client *);
extern struct nfs_server *nfs_create_server(
const struct nfs_parsed_mount_data *,
struct nfs_fh *);
extern struct nfs_server *nfs4_create_server(
const struct nfs_parsed_mount_data *,
struct nfs_fh *);
extern struct nfs_server *nfs4_create_referral_server(struct nfs_clone_mount *,
struct nfs_fh *);
extern void nfs_free_server(struct nfs_server *server);
extern struct nfs_server *nfs_clone_server(struct nfs_server *,
struct nfs_fh *,
struct nfs_fattr *);
#ifdef CONFIG_PROC_FS
extern int __init nfs_fs_proc_init(void);
extern void nfs_fs_proc_exit(void);
#else
static inline int nfs_fs_proc_init(void)
{
return 0;
}
static inline void nfs_fs_proc_exit(void)
{
}
#endif
/* nfs4namespace.c */
#ifdef CONFIG_NFS_V4
extern struct vfsmount *nfs_do_refmount(const struct vfsmount *mnt_parent, struct dentry *dentry);
#else
static inline
struct vfsmount *nfs_do_refmount(const struct vfsmount *mnt_parent, struct dentry *dentry)
{
return ERR_PTR(-ENOENT);
}
#endif
/* callback_xdr.c */
extern struct svc_version nfs4_callback_version1;
/* pagelist.c */
extern int __init nfs_init_nfspagecache(void);
extern void nfs_destroy_nfspagecache(void);
extern int __init nfs_init_readpagecache(void);
extern void nfs_destroy_readpagecache(void);
extern int __init nfs_init_writepagecache(void);
extern void nfs_destroy_writepagecache(void);
extern int __init nfs_init_directcache(void);
extern void nfs_destroy_directcache(void);
/* nfs2xdr.c */
extern int nfs_stat_to_errno(int);
extern struct rpc_procinfo nfs_procedures[];
extern __be32 * nfs_decode_dirent(__be32 *, struct nfs_entry *, int);
/* nfs3xdr.c */
extern struct rpc_procinfo nfs3_procedures[];
extern __be32 *nfs3_decode_dirent(__be32 *, struct nfs_entry *, int);
/* nfs4xdr.c */
#ifdef CONFIG_NFS_V4
extern __be32 *nfs4_decode_dirent(__be32 *p, struct nfs_entry *entry, int plus);
#endif
/* nfs4proc.c */
#ifdef CONFIG_NFS_V4
extern struct rpc_procinfo nfs4_procedures[];
#endif
/* dir.c */
extern int nfs_access_cache_shrinker(int nr_to_scan, gfp_t gfp_mask);
/* inode.c */
extern struct workqueue_struct *nfsiod_workqueue;
extern struct inode *nfs_alloc_inode(struct super_block *sb);
extern void nfs_destroy_inode(struct inode *);
extern int nfs_write_inode(struct inode *,int);
extern void nfs_clear_inode(struct inode *);
#ifdef CONFIG_NFS_V4
extern void nfs4_clear_inode(struct inode *);
#endif
void nfs_zap_acl_cache(struct inode *inode);
extern int nfs_wait_bit_killable(void *word);
/* super.c */
void nfs_parse_ip_address(char *, size_t, struct sockaddr *, size_t *);
extern struct file_system_type nfs_xdev_fs_type;
#ifdef CONFIG_NFS_V4
extern struct file_system_type nfs4_xdev_fs_type;
extern struct file_system_type nfs4_referral_fs_type;
#endif
extern struct rpc_stat nfs_rpcstat;
extern int __init register_nfs_fs(void);
extern void __exit unregister_nfs_fs(void);
extern void nfs_sb_active(struct super_block *sb);
extern void nfs_sb_deactive(struct super_block *sb);
/* namespace.c */
extern char *nfs_path(const char *base,
const struct dentry *droot,
const struct dentry *dentry,
char *buffer, ssize_t buflen);
/* getroot.c */
extern struct dentry *nfs_get_root(struct super_block *, struct nfs_fh *);
#ifdef CONFIG_NFS_V4
extern struct dentry *nfs4_get_root(struct super_block *, struct nfs_fh *);
extern int nfs4_path_walk(struct nfs_server *server,
struct nfs_fh *mntfh,
const char *path);
#endif
/*
* Determine the device name as a string
*/
static inline char *nfs_devname(const struct vfsmount *mnt_parent,
const struct dentry *dentry,
char *buffer, ssize_t buflen)
{
return nfs_path(mnt_parent->mnt_devname, mnt_parent->mnt_root,
dentry, buffer, buflen);
}
/*
* Determine the actual block size (and log2 thereof)
*/
static inline
unsigned long nfs_block_bits(unsigned long bsize, unsigned char *nrbitsp)
{
/* make sure blocksize is a power of two */
if ((bsize & (bsize - 1)) || nrbitsp) {
unsigned char nrbits;
for (nrbits = 31; nrbits && !(bsize & (1 << nrbits)); nrbits--)
;
bsize = 1 << nrbits;
if (nrbitsp)
*nrbitsp = nrbits;
}
return bsize;
}
/*
* Calculate the number of 512byte blocks used.
*/
static inline blkcnt_t nfs_calc_block_size(u64 tsize)
{
blkcnt_t used = (tsize + 511) >> 9;
return (used > ULONG_MAX) ? ULONG_MAX : used;
}
/*
* Compute and set NFS server blocksize
*/
static inline
unsigned long nfs_block_size(unsigned long bsize, unsigned char *nrbitsp)
{
if (bsize < NFS_MIN_FILE_IO_SIZE)
bsize = NFS_DEF_FILE_IO_SIZE;
else if (bsize >= NFS_MAX_FILE_IO_SIZE)
bsize = NFS_MAX_FILE_IO_SIZE;
return nfs_block_bits(bsize, nrbitsp);
}
/*
* Determine the maximum file size for a superblock
*/
static inline
void nfs_super_set_maxbytes(struct super_block *sb, __u64 maxfilesize)
{
sb->s_maxbytes = (loff_t)maxfilesize;
if (sb->s_maxbytes > MAX_LFS_FILESIZE || sb->s_maxbytes <= 0)
sb->s_maxbytes = MAX_LFS_FILESIZE;
}
/*
* Determine the number of bytes of data the page contains
*/
static inline
unsigned int nfs_page_length(struct page *page)
{
loff_t i_size = i_size_read(page->mapping->host);
if (i_size > 0) {
pgoff_t end_index = (i_size - 1) >> PAGE_CACHE_SHIFT;
if (page->index < end_index)
return PAGE_CACHE_SIZE;
if (page->index == end_index)
return ((i_size - 1) & ~PAGE_CACHE_MASK) + 1;
}
return 0;
}
/*
* Determine the number of pages in an array of length 'len' and
* with a base offset of 'base'
*/
static inline
unsigned int nfs_page_array_len(unsigned int base, size_t len)
{
return ((unsigned long)len + (unsigned long)base +
PAGE_SIZE - 1) >> PAGE_SHIFT;
}
#define IPV6_SCOPE_DELIMITER '%'
/*
* Set the port number in an address. Be agnostic about the address
* family.
*/
static inline void nfs_set_port(struct sockaddr *sap, unsigned short port)
{
struct sockaddr_in *ap = (struct sockaddr_in *)sap;
struct sockaddr_in6 *ap6 = (struct sockaddr_in6 *)sap;
switch (sap->sa_family) {
case AF_INET:
ap->sin_port = htons(port);
break;
case AF_INET6:
ap6->sin6_port = htons(port);
break;
}
}
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