linux/fs/nfs/file.c
Mel Gorman f919b19614 fs: nfs: inform the VM about pages being committed or unstable
VM page reclaim uses dirty and writeback page states to determine if
flushers are cleaning pages too slowly and that page reclaim should
stall waiting on flushers to catch up.  Page state in NFS is a bit more
complex and a clean page can be unreclaimable due to being unstable
which is effectively "dirty" from the perspective of the VM from reclaim
context.  Similarly, if the inode is currently being committed then it's
similar to being under writeback.

This patch adds a is_dirty_writeback() handled for NFS that checks if a
pages backing inode is being committed and should be accounted as
writeback and if a page has private state indicating that it is
effectively dirty.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Rik van Riel <riel@redhat.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
Cc: Zlatko Calusic <zcalusic@bitsync.net>
Cc: dormando <dormando@rydia.net>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-03 16:07:29 -07:00

971 lines
26 KiB
C

/*
* linux/fs/nfs/file.c
*
* Copyright (C) 1992 Rick Sladkey
*
* Changes Copyright (C) 1994 by Florian La Roche
* - Do not copy data too often around in the kernel.
* - In nfs_file_read the return value of kmalloc wasn't checked.
* - Put in a better version of read look-ahead buffering. Original idea
* and implementation by Wai S Kok elekokws@ee.nus.sg.
*
* Expire cache on write to a file by Wai S Kok (Oct 1994).
*
* Total rewrite of read side for new NFS buffer cache.. Linus.
*
* nfs regular file handling functions
*/
#include <linux/module.h>
#include <linux/time.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/fcntl.h>
#include <linux/stat.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_mount.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/aio.h>
#include <linux/gfp.h>
#include <linux/swap.h>
#include <asm/uaccess.h>
#include "delegation.h"
#include "internal.h"
#include "iostat.h"
#include "fscache.h"
#define NFSDBG_FACILITY NFSDBG_FILE
static const struct vm_operations_struct nfs_file_vm_ops;
/* Hack for future NFS swap support */
#ifndef IS_SWAPFILE
# define IS_SWAPFILE(inode) (0)
#endif
int nfs_check_flags(int flags)
{
if ((flags & (O_APPEND | O_DIRECT)) == (O_APPEND | O_DIRECT))
return -EINVAL;
return 0;
}
EXPORT_SYMBOL_GPL(nfs_check_flags);
/*
* Open file
*/
static int
nfs_file_open(struct inode *inode, struct file *filp)
{
int res;
dprintk("NFS: open file(%s/%s)\n",
filp->f_path.dentry->d_parent->d_name.name,
filp->f_path.dentry->d_name.name);
nfs_inc_stats(inode, NFSIOS_VFSOPEN);
res = nfs_check_flags(filp->f_flags);
if (res)
return res;
res = nfs_open(inode, filp);
return res;
}
int
nfs_file_release(struct inode *inode, struct file *filp)
{
dprintk("NFS: release(%s/%s)\n",
filp->f_path.dentry->d_parent->d_name.name,
filp->f_path.dentry->d_name.name);
nfs_inc_stats(inode, NFSIOS_VFSRELEASE);
return nfs_release(inode, filp);
}
EXPORT_SYMBOL_GPL(nfs_file_release);
/**
* nfs_revalidate_size - Revalidate the file size
* @inode - pointer to inode struct
* @file - pointer to struct file
*
* Revalidates the file length. This is basically a wrapper around
* nfs_revalidate_inode() that takes into account the fact that we may
* have cached writes (in which case we don't care about the server's
* idea of what the file length is), or O_DIRECT (in which case we
* shouldn't trust the cache).
*/
static int nfs_revalidate_file_size(struct inode *inode, struct file *filp)
{
struct nfs_server *server = NFS_SERVER(inode);
struct nfs_inode *nfsi = NFS_I(inode);
if (nfs_have_delegated_attributes(inode))
goto out_noreval;
if (filp->f_flags & O_DIRECT)
goto force_reval;
if (nfsi->cache_validity & NFS_INO_REVAL_PAGECACHE)
goto force_reval;
if (nfs_attribute_timeout(inode))
goto force_reval;
out_noreval:
return 0;
force_reval:
return __nfs_revalidate_inode(server, inode);
}
loff_t nfs_file_llseek(struct file *filp, loff_t offset, int whence)
{
dprintk("NFS: llseek file(%s/%s, %lld, %d)\n",
filp->f_path.dentry->d_parent->d_name.name,
filp->f_path.dentry->d_name.name,
offset, whence);
/*
* whence == SEEK_END || SEEK_DATA || SEEK_HOLE => we must revalidate
* the cached file length
*/
if (whence != SEEK_SET && whence != SEEK_CUR) {
struct inode *inode = filp->f_mapping->host;
int retval = nfs_revalidate_file_size(inode, filp);
if (retval < 0)
return (loff_t)retval;
}
return generic_file_llseek(filp, offset, whence);
}
EXPORT_SYMBOL_GPL(nfs_file_llseek);
/*
* Flush all dirty pages, and check for write errors.
*/
int
nfs_file_flush(struct file *file, fl_owner_t id)
{
struct dentry *dentry = file->f_path.dentry;
struct inode *inode = dentry->d_inode;
dprintk("NFS: flush(%s/%s)\n",
dentry->d_parent->d_name.name,
dentry->d_name.name);
nfs_inc_stats(inode, NFSIOS_VFSFLUSH);
if ((file->f_mode & FMODE_WRITE) == 0)
return 0;
/*
* If we're holding a write delegation, then just start the i/o
* but don't wait for completion (or send a commit).
*/
if (NFS_PROTO(inode)->have_delegation(inode, FMODE_WRITE))
return filemap_fdatawrite(file->f_mapping);
/* Flush writes to the server and return any errors */
return vfs_fsync(file, 0);
}
EXPORT_SYMBOL_GPL(nfs_file_flush);
ssize_t
nfs_file_read(struct kiocb *iocb, const struct iovec *iov,
unsigned long nr_segs, loff_t pos)
{
struct dentry * dentry = iocb->ki_filp->f_path.dentry;
struct inode * inode = dentry->d_inode;
ssize_t result;
if (iocb->ki_filp->f_flags & O_DIRECT)
return nfs_file_direct_read(iocb, iov, nr_segs, pos, true);
dprintk("NFS: read(%s/%s, %lu@%lu)\n",
dentry->d_parent->d_name.name, dentry->d_name.name,
(unsigned long) iov_length(iov, nr_segs), (unsigned long) pos);
result = nfs_revalidate_mapping(inode, iocb->ki_filp->f_mapping);
if (!result) {
result = generic_file_aio_read(iocb, iov, nr_segs, pos);
if (result > 0)
nfs_add_stats(inode, NFSIOS_NORMALREADBYTES, result);
}
return result;
}
EXPORT_SYMBOL_GPL(nfs_file_read);
ssize_t
nfs_file_splice_read(struct file *filp, loff_t *ppos,
struct pipe_inode_info *pipe, size_t count,
unsigned int flags)
{
struct dentry *dentry = filp->f_path.dentry;
struct inode *inode = dentry->d_inode;
ssize_t res;
dprintk("NFS: splice_read(%s/%s, %lu@%Lu)\n",
dentry->d_parent->d_name.name, dentry->d_name.name,
(unsigned long) count, (unsigned long long) *ppos);
res = nfs_revalidate_mapping(inode, filp->f_mapping);
if (!res) {
res = generic_file_splice_read(filp, ppos, pipe, count, flags);
if (res > 0)
nfs_add_stats(inode, NFSIOS_NORMALREADBYTES, res);
}
return res;
}
EXPORT_SYMBOL_GPL(nfs_file_splice_read);
int
nfs_file_mmap(struct file * file, struct vm_area_struct * vma)
{
struct dentry *dentry = file->f_path.dentry;
struct inode *inode = dentry->d_inode;
int status;
dprintk("NFS: mmap(%s/%s)\n",
dentry->d_parent->d_name.name, dentry->d_name.name);
/* Note: generic_file_mmap() returns ENOSYS on nommu systems
* so we call that before revalidating the mapping
*/
status = generic_file_mmap(file, vma);
if (!status) {
vma->vm_ops = &nfs_file_vm_ops;
status = nfs_revalidate_mapping(inode, file->f_mapping);
}
return status;
}
EXPORT_SYMBOL_GPL(nfs_file_mmap);
/*
* Flush any dirty pages for this process, and check for write errors.
* The return status from this call provides a reliable indication of
* whether any write errors occurred for this process.
*
* Notice that it clears the NFS_CONTEXT_ERROR_WRITE before synching to
* disk, but it retrieves and clears ctx->error after synching, despite
* the two being set at the same time in nfs_context_set_write_error().
* This is because the former is used to notify the _next_ call to
* nfs_file_write() that a write error occurred, and hence cause it to
* fall back to doing a synchronous write.
*/
int
nfs_file_fsync_commit(struct file *file, loff_t start, loff_t end, int datasync)
{
struct dentry *dentry = file->f_path.dentry;
struct nfs_open_context *ctx = nfs_file_open_context(file);
struct inode *inode = dentry->d_inode;
int have_error, do_resend, status;
int ret = 0;
dprintk("NFS: fsync file(%s/%s) datasync %d\n",
dentry->d_parent->d_name.name, dentry->d_name.name,
datasync);
nfs_inc_stats(inode, NFSIOS_VFSFSYNC);
do_resend = test_and_clear_bit(NFS_CONTEXT_RESEND_WRITES, &ctx->flags);
have_error = test_and_clear_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags);
status = nfs_commit_inode(inode, FLUSH_SYNC);
have_error |= test_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags);
if (have_error) {
ret = xchg(&ctx->error, 0);
if (ret)
goto out;
}
if (status < 0) {
ret = status;
goto out;
}
do_resend |= test_bit(NFS_CONTEXT_RESEND_WRITES, &ctx->flags);
if (do_resend)
ret = -EAGAIN;
out:
return ret;
}
EXPORT_SYMBOL_GPL(nfs_file_fsync_commit);
static int
nfs_file_fsync(struct file *file, loff_t start, loff_t end, int datasync)
{
int ret;
struct inode *inode = file_inode(file);
do {
ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
if (ret != 0)
break;
mutex_lock(&inode->i_mutex);
ret = nfs_file_fsync_commit(file, start, end, datasync);
mutex_unlock(&inode->i_mutex);
/*
* If nfs_file_fsync_commit detected a server reboot, then
* resend all dirty pages that might have been covered by
* the NFS_CONTEXT_RESEND_WRITES flag
*/
start = 0;
end = LLONG_MAX;
} while (ret == -EAGAIN);
return ret;
}
/*
* Decide whether a read/modify/write cycle may be more efficient
* then a modify/write/read cycle when writing to a page in the
* page cache.
*
* The modify/write/read cycle may occur if a page is read before
* being completely filled by the writer. In this situation, the
* page must be completely written to stable storage on the server
* before it can be refilled by reading in the page from the server.
* This can lead to expensive, small, FILE_SYNC mode writes being
* done.
*
* It may be more efficient to read the page first if the file is
* open for reading in addition to writing, the page is not marked
* as Uptodate, it is not dirty or waiting to be committed,
* indicating that it was previously allocated and then modified,
* that there were valid bytes of data in that range of the file,
* and that the new data won't completely replace the old data in
* that range of the file.
*/
static int nfs_want_read_modify_write(struct file *file, struct page *page,
loff_t pos, unsigned len)
{
unsigned int pglen = nfs_page_length(page);
unsigned int offset = pos & (PAGE_CACHE_SIZE - 1);
unsigned int end = offset + len;
if ((file->f_mode & FMODE_READ) && /* open for read? */
!PageUptodate(page) && /* Uptodate? */
!PagePrivate(page) && /* i/o request already? */
pglen && /* valid bytes of file? */
(end < pglen || offset)) /* replace all valid bytes? */
return 1;
return 0;
}
/*
* This does the "real" work of the write. We must allocate and lock the
* page to be sent back to the generic routine, which then copies the
* data from user space.
*
* If the writer ends up delaying the write, the writer needs to
* increment the page use counts until he is done with the page.
*/
static int nfs_write_begin(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned flags,
struct page **pagep, void **fsdata)
{
int ret;
pgoff_t index = pos >> PAGE_CACHE_SHIFT;
struct page *page;
int once_thru = 0;
dfprintk(PAGECACHE, "NFS: write_begin(%s/%s(%ld), %u@%lld)\n",
file->f_path.dentry->d_parent->d_name.name,
file->f_path.dentry->d_name.name,
mapping->host->i_ino, len, (long long) pos);
start:
/*
* Prevent starvation issues if someone is doing a consistency
* sync-to-disk
*/
ret = wait_on_bit(&NFS_I(mapping->host)->flags, NFS_INO_FLUSHING,
nfs_wait_bit_killable, TASK_KILLABLE);
if (ret)
return ret;
page = grab_cache_page_write_begin(mapping, index, flags);
if (!page)
return -ENOMEM;
*pagep = page;
ret = nfs_flush_incompatible(file, page);
if (ret) {
unlock_page(page);
page_cache_release(page);
} else if (!once_thru &&
nfs_want_read_modify_write(file, page, pos, len)) {
once_thru = 1;
ret = nfs_readpage(file, page);
page_cache_release(page);
if (!ret)
goto start;
}
return ret;
}
static int nfs_write_end(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned copied,
struct page *page, void *fsdata)
{
unsigned offset = pos & (PAGE_CACHE_SIZE - 1);
int status;
dfprintk(PAGECACHE, "NFS: write_end(%s/%s(%ld), %u@%lld)\n",
file->f_path.dentry->d_parent->d_name.name,
file->f_path.dentry->d_name.name,
mapping->host->i_ino, len, (long long) pos);
/*
* Zero any uninitialised parts of the page, and then mark the page
* as up to date if it turns out that we're extending the file.
*/
if (!PageUptodate(page)) {
unsigned pglen = nfs_page_length(page);
unsigned end = offset + len;
if (pglen == 0) {
zero_user_segments(page, 0, offset,
end, PAGE_CACHE_SIZE);
SetPageUptodate(page);
} else if (end >= pglen) {
zero_user_segment(page, end, PAGE_CACHE_SIZE);
if (offset == 0)
SetPageUptodate(page);
} else
zero_user_segment(page, pglen, PAGE_CACHE_SIZE);
}
status = nfs_updatepage(file, page, offset, copied);
unlock_page(page);
page_cache_release(page);
if (status < 0)
return status;
NFS_I(mapping->host)->write_io += copied;
return copied;
}
/*
* Partially or wholly invalidate a page
* - Release the private state associated with a page if undergoing complete
* page invalidation
* - Called if either PG_private or PG_fscache is set on the page
* - Caller holds page lock
*/
static void nfs_invalidate_page(struct page *page, unsigned int offset,
unsigned int length)
{
dfprintk(PAGECACHE, "NFS: invalidate_page(%p, %u, %u)\n",
page, offset, length);
if (offset != 0 || length < PAGE_CACHE_SIZE)
return;
/* Cancel any unstarted writes on this page */
nfs_wb_page_cancel(page_file_mapping(page)->host, page);
nfs_fscache_invalidate_page(page, page->mapping->host);
}
/*
* Attempt to release the private state associated with a page
* - Called if either PG_private or PG_fscache is set on the page
* - Caller holds page lock
* - Return true (may release page) or false (may not)
*/
static int nfs_release_page(struct page *page, gfp_t gfp)
{
struct address_space *mapping = page->mapping;
dfprintk(PAGECACHE, "NFS: release_page(%p)\n", page);
/* Only do I/O if gfp is a superset of GFP_KERNEL, and we're not
* doing this memory reclaim for a fs-related allocation.
*/
if (mapping && (gfp & GFP_KERNEL) == GFP_KERNEL &&
!(current->flags & PF_FSTRANS)) {
int how = FLUSH_SYNC;
/* Don't let kswapd deadlock waiting for OOM RPC calls */
if (current_is_kswapd())
how = 0;
nfs_commit_inode(mapping->host, how);
}
/* If PagePrivate() is set, then the page is not freeable */
if (PagePrivate(page))
return 0;
return nfs_fscache_release_page(page, gfp);
}
static void nfs_check_dirty_writeback(struct page *page,
bool *dirty, bool *writeback)
{
struct nfs_inode *nfsi;
struct address_space *mapping = page_file_mapping(page);
if (!mapping || PageSwapCache(page))
return;
/*
* Check if an unstable page is currently being committed and
* if so, have the VM treat it as if the page is under writeback
* so it will not block due to pages that will shortly be freeable.
*/
nfsi = NFS_I(mapping->host);
if (test_bit(NFS_INO_COMMIT, &nfsi->flags)) {
*writeback = true;
return;
}
/*
* If PagePrivate() is set, then the page is not freeable and as the
* inode is not being committed, it's not going to be cleaned in the
* near future so treat it as dirty
*/
if (PagePrivate(page))
*dirty = true;
}
/*
* Attempt to clear the private state associated with a page when an error
* occurs that requires the cached contents of an inode to be written back or
* destroyed
* - Called if either PG_private or fscache is set on the page
* - Caller holds page lock
* - Return 0 if successful, -error otherwise
*/
static int nfs_launder_page(struct page *page)
{
struct inode *inode = page_file_mapping(page)->host;
struct nfs_inode *nfsi = NFS_I(inode);
dfprintk(PAGECACHE, "NFS: launder_page(%ld, %llu)\n",
inode->i_ino, (long long)page_offset(page));
nfs_fscache_wait_on_page_write(nfsi, page);
return nfs_wb_page(inode, page);
}
#ifdef CONFIG_NFS_SWAP
static int nfs_swap_activate(struct swap_info_struct *sis, struct file *file,
sector_t *span)
{
*span = sis->pages;
return xs_swapper(NFS_CLIENT(file->f_mapping->host)->cl_xprt, 1);
}
static void nfs_swap_deactivate(struct file *file)
{
xs_swapper(NFS_CLIENT(file->f_mapping->host)->cl_xprt, 0);
}
#endif
const struct address_space_operations nfs_file_aops = {
.readpage = nfs_readpage,
.readpages = nfs_readpages,
.set_page_dirty = __set_page_dirty_nobuffers,
.writepage = nfs_writepage,
.writepages = nfs_writepages,
.write_begin = nfs_write_begin,
.write_end = nfs_write_end,
.invalidatepage = nfs_invalidate_page,
.releasepage = nfs_release_page,
.direct_IO = nfs_direct_IO,
.migratepage = nfs_migrate_page,
.launder_page = nfs_launder_page,
.is_dirty_writeback = nfs_check_dirty_writeback,
.error_remove_page = generic_error_remove_page,
#ifdef CONFIG_NFS_SWAP
.swap_activate = nfs_swap_activate,
.swap_deactivate = nfs_swap_deactivate,
#endif
};
/*
* Notification that a PTE pointing to an NFS page is about to be made
* writable, implying that someone is about to modify the page through a
* shared-writable mapping
*/
static int nfs_vm_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
{
struct page *page = vmf->page;
struct file *filp = vma->vm_file;
struct dentry *dentry = filp->f_path.dentry;
unsigned pagelen;
int ret = VM_FAULT_NOPAGE;
struct address_space *mapping;
dfprintk(PAGECACHE, "NFS: vm_page_mkwrite(%s/%s(%ld), offset %lld)\n",
dentry->d_parent->d_name.name, dentry->d_name.name,
filp->f_mapping->host->i_ino,
(long long)page_offset(page));
/* make sure the cache has finished storing the page */
nfs_fscache_wait_on_page_write(NFS_I(dentry->d_inode), page);
lock_page(page);
mapping = page_file_mapping(page);
if (mapping != dentry->d_inode->i_mapping)
goto out_unlock;
wait_on_page_writeback(page);
pagelen = nfs_page_length(page);
if (pagelen == 0)
goto out_unlock;
ret = VM_FAULT_LOCKED;
if (nfs_flush_incompatible(filp, page) == 0 &&
nfs_updatepage(filp, page, 0, pagelen) == 0)
goto out;
ret = VM_FAULT_SIGBUS;
out_unlock:
unlock_page(page);
out:
return ret;
}
static const struct vm_operations_struct nfs_file_vm_ops = {
.fault = filemap_fault,
.page_mkwrite = nfs_vm_page_mkwrite,
.remap_pages = generic_file_remap_pages,
};
static int nfs_need_sync_write(struct file *filp, struct inode *inode)
{
struct nfs_open_context *ctx;
if (IS_SYNC(inode) || (filp->f_flags & O_DSYNC))
return 1;
ctx = nfs_file_open_context(filp);
if (test_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags))
return 1;
return 0;
}
ssize_t nfs_file_write(struct kiocb *iocb, const struct iovec *iov,
unsigned long nr_segs, loff_t pos)
{
struct dentry * dentry = iocb->ki_filp->f_path.dentry;
struct inode * inode = dentry->d_inode;
unsigned long written = 0;
ssize_t result;
size_t count = iov_length(iov, nr_segs);
if (iocb->ki_filp->f_flags & O_DIRECT)
return nfs_file_direct_write(iocb, iov, nr_segs, pos, true);
dprintk("NFS: write(%s/%s, %lu@%Ld)\n",
dentry->d_parent->d_name.name, dentry->d_name.name,
(unsigned long) count, (long long) pos);
result = -EBUSY;
if (IS_SWAPFILE(inode))
goto out_swapfile;
/*
* O_APPEND implies that we must revalidate the file length.
*/
if (iocb->ki_filp->f_flags & O_APPEND) {
result = nfs_revalidate_file_size(inode, iocb->ki_filp);
if (result)
goto out;
}
result = count;
if (!count)
goto out;
result = generic_file_aio_write(iocb, iov, nr_segs, pos);
if (result > 0)
written = result;
/* Return error values for O_DSYNC and IS_SYNC() */
if (result >= 0 && nfs_need_sync_write(iocb->ki_filp, inode)) {
int err = vfs_fsync(iocb->ki_filp, 0);
if (err < 0)
result = err;
}
if (result > 0)
nfs_add_stats(inode, NFSIOS_NORMALWRITTENBYTES, written);
out:
return result;
out_swapfile:
printk(KERN_INFO "NFS: attempt to write to active swap file!\n");
goto out;
}
EXPORT_SYMBOL_GPL(nfs_file_write);
ssize_t nfs_file_splice_write(struct pipe_inode_info *pipe,
struct file *filp, loff_t *ppos,
size_t count, unsigned int flags)
{
struct dentry *dentry = filp->f_path.dentry;
struct inode *inode = dentry->d_inode;
unsigned long written = 0;
ssize_t ret;
dprintk("NFS splice_write(%s/%s, %lu@%llu)\n",
dentry->d_parent->d_name.name, dentry->d_name.name,
(unsigned long) count, (unsigned long long) *ppos);
/*
* The combination of splice and an O_APPEND destination is disallowed.
*/
ret = generic_file_splice_write(pipe, filp, ppos, count, flags);
if (ret > 0)
written = ret;
if (ret >= 0 && nfs_need_sync_write(filp, inode)) {
int err = vfs_fsync(filp, 0);
if (err < 0)
ret = err;
}
if (ret > 0)
nfs_add_stats(inode, NFSIOS_NORMALWRITTENBYTES, written);
return ret;
}
EXPORT_SYMBOL_GPL(nfs_file_splice_write);
static int
do_getlk(struct file *filp, int cmd, struct file_lock *fl, int is_local)
{
struct inode *inode = filp->f_mapping->host;
int status = 0;
unsigned int saved_type = fl->fl_type;
/* Try local locking first */
posix_test_lock(filp, fl);
if (fl->fl_type != F_UNLCK) {
/* found a conflict */
goto out;
}
fl->fl_type = saved_type;
if (NFS_PROTO(inode)->have_delegation(inode, FMODE_READ))
goto out_noconflict;
if (is_local)
goto out_noconflict;
status = NFS_PROTO(inode)->lock(filp, cmd, fl);
out:
return status;
out_noconflict:
fl->fl_type = F_UNLCK;
goto out;
}
static int do_vfs_lock(struct file *file, struct file_lock *fl)
{
int res = 0;
switch (fl->fl_flags & (FL_POSIX|FL_FLOCK)) {
case FL_POSIX:
res = posix_lock_file_wait(file, fl);
break;
case FL_FLOCK:
res = flock_lock_file_wait(file, fl);
break;
default:
BUG();
}
return res;
}
static int
do_unlk(struct file *filp, int cmd, struct file_lock *fl, int is_local)
{
struct inode *inode = filp->f_mapping->host;
struct nfs_lock_context *l_ctx;
int status;
/*
* Flush all pending writes before doing anything
* with locks..
*/
nfs_sync_mapping(filp->f_mapping);
l_ctx = nfs_get_lock_context(nfs_file_open_context(filp));
if (!IS_ERR(l_ctx)) {
status = nfs_iocounter_wait(&l_ctx->io_count);
nfs_put_lock_context(l_ctx);
if (status < 0)
return status;
}
/* NOTE: special case
* If we're signalled while cleaning up locks on process exit, we
* still need to complete the unlock.
*/
/*
* Use local locking if mounted with "-onolock" or with appropriate
* "-olocal_lock="
*/
if (!is_local)
status = NFS_PROTO(inode)->lock(filp, cmd, fl);
else
status = do_vfs_lock(filp, fl);
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)
{
struct inode *inode = filp->f_mapping->host;
int status;
/*
* Flush all pending writes before doing anything
* with locks..
*/
status = nfs_sync_mapping(filp->f_mapping);
if (status != 0)
goto out;
/*
* Use local locking if mounted with "-onolock" or with appropriate
* "-olocal_lock="
*/
if (!is_local)
status = NFS_PROTO(inode)->lock(filp, cmd, fl);
else
status = do_vfs_lock(filp, fl);
if (status < 0)
goto out;
/*
* Revalidate the cache if the server has time stamps granular
* enough to detect subsecond changes. Otherwise, clear the
* cache to prevent missing any changes.
*
* 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);
}
out:
return status;
}
/*
* Lock a (portion of) a file
*/
int nfs_lock(struct file *filp, int cmd, struct file_lock *fl)
{
struct inode *inode = filp->f_mapping->host;
int ret = -ENOLCK;
int is_local = 0;
dprintk("NFS: lock(%s/%s, t=%x, fl=%x, r=%lld:%lld)\n",
filp->f_path.dentry->d_parent->d_name.name,
filp->f_path.dentry->d_name.name,
fl->fl_type, fl->fl_flags,
(long long)fl->fl_start, (long long)fl->fl_end);
nfs_inc_stats(inode, NFSIOS_VFSLOCK);
/* No mandatory locks over NFS */
if (__mandatory_lock(inode) && fl->fl_type != F_UNLCK)
goto out_err;
if (NFS_SERVER(inode)->flags & NFS_MOUNT_LOCAL_FCNTL)
is_local = 1;
if (NFS_PROTO(inode)->lock_check_bounds != NULL) {
ret = NFS_PROTO(inode)->lock_check_bounds(fl);
if (ret < 0)
goto out_err;
}
if (IS_GETLK(cmd))
ret = do_getlk(filp, cmd, fl, is_local);
else if (fl->fl_type == F_UNLCK)
ret = do_unlk(filp, cmd, fl, is_local);
else
ret = do_setlk(filp, cmd, fl, is_local);
out_err:
return ret;
}
EXPORT_SYMBOL_GPL(nfs_lock);
/*
* Lock a (portion of) a file
*/
int nfs_flock(struct file *filp, int cmd, struct file_lock *fl)
{
struct inode *inode = filp->f_mapping->host;
int is_local = 0;
dprintk("NFS: flock(%s/%s, t=%x, fl=%x)\n",
filp->f_path.dentry->d_parent->d_name.name,
filp->f_path.dentry->d_name.name,
fl->fl_type, fl->fl_flags);
if (!(fl->fl_flags & FL_FLOCK))
return -ENOLCK;
/*
* The NFSv4 protocol doesn't support LOCK_MAND, which is not part of
* any standard. In principle we might be able to support LOCK_MAND
* on NFSv2/3 since NLMv3/4 support DOS share modes, but for now the
* NFS code is not set up for it.
*/
if (fl->fl_type & LOCK_MAND)
return -EINVAL;
if (NFS_SERVER(inode)->flags & NFS_MOUNT_LOCAL_FLOCK)
is_local = 1;
/* We're simulating flock() locks using posix locks on the server */
fl->fl_owner = (fl_owner_t)filp;
fl->fl_start = 0;
fl->fl_end = OFFSET_MAX;
if (fl->fl_type == F_UNLCK)
return do_unlk(filp, cmd, fl, is_local);
return do_setlk(filp, cmd, fl, is_local);
}
EXPORT_SYMBOL_GPL(nfs_flock);
/*
* There is no protocol support for leases, so we have no way to implement
* them correctly in the face of opens by other clients.
*/
int nfs_setlease(struct file *file, long arg, struct file_lock **fl)
{
dprintk("NFS: setlease(%s/%s, arg=%ld)\n",
file->f_path.dentry->d_parent->d_name.name,
file->f_path.dentry->d_name.name, arg);
return -EINVAL;
}
EXPORT_SYMBOL_GPL(nfs_setlease);
const struct file_operations nfs_file_operations = {
.llseek = nfs_file_llseek,
.read = do_sync_read,
.write = do_sync_write,
.aio_read = nfs_file_read,
.aio_write = nfs_file_write,
.mmap = nfs_file_mmap,
.open = nfs_file_open,
.flush = nfs_file_flush,
.release = nfs_file_release,
.fsync = nfs_file_fsync,
.lock = nfs_lock,
.flock = nfs_flock,
.splice_read = nfs_file_splice_read,
.splice_write = nfs_file_splice_write,
.check_flags = nfs_check_flags,
.setlease = nfs_setlease,
};
EXPORT_SYMBOL_GPL(nfs_file_operations);