// SPDX-License-Identifier: GPL-2.0-only /* * 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 #include #include #include #include #include #include #include #include #include #include #include #include #include "delegation.h" #include "internal.h" #include "iostat.h" #include "fscache.h" #include "pnfs.h" #include "nfstrace.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(%pD2)\n", filp); 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(%pD2)\n", filp); nfs_inc_stats(inode, NFSIOS_VFSRELEASE); nfs_file_clear_open_context(filp); return 0; } EXPORT_SYMBOL_GPL(nfs_file_release); /** * nfs_revalidate_file_size - Revalidate the file size * @inode: pointer to inode struct * @filp: 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); if (filp->f_flags & O_DIRECT) goto force_reval; if (nfs_check_cache_invalid(inode, NFS_INO_REVAL_PAGECACHE)) goto force_reval; 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(%pD2, %lld, %d)\n", filp, 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. */ static int nfs_file_flush(struct file *file, fl_owner_t id) { struct inode *inode = file_inode(file); errseq_t since; dprintk("NFS: flush(%pD2)\n", file); nfs_inc_stats(inode, NFSIOS_VFSFLUSH); if ((file->f_mode & FMODE_WRITE) == 0) return 0; /* Flush writes to the server and return any errors */ since = filemap_sample_wb_err(file->f_mapping); nfs_wb_all(inode); return filemap_check_wb_err(file->f_mapping, since); } ssize_t nfs_file_read(struct kiocb *iocb, struct iov_iter *to) { struct inode *inode = file_inode(iocb->ki_filp); ssize_t result; if (iocb->ki_flags & IOCB_DIRECT) return nfs_file_direct_read(iocb, to); dprintk("NFS: read(%pD2, %zu@%lu)\n", iocb->ki_filp, iov_iter_count(to), (unsigned long) iocb->ki_pos); nfs_start_io_read(inode); result = nfs_revalidate_mapping(inode, iocb->ki_filp->f_mapping); if (!result) { result = generic_file_read_iter(iocb, to); if (result > 0) nfs_add_stats(inode, NFSIOS_NORMALREADBYTES, result); } nfs_end_io_read(inode); return result; } EXPORT_SYMBOL_GPL(nfs_file_read); int nfs_file_mmap(struct file * file, struct vm_area_struct * vma) { struct inode *inode = file_inode(file); int status; dprintk("NFS: mmap(%pD2)\n", file); /* 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. */ static int nfs_file_fsync_commit(struct file *file, int datasync) { struct inode *inode = file_inode(file); int ret; dprintk("NFS: fsync file(%pD2) datasync %d\n", file, datasync); nfs_inc_stats(inode, NFSIOS_VFSFSYNC); ret = nfs_commit_inode(inode, FLUSH_SYNC); if (ret < 0) return ret; return file_check_and_advance_wb_err(file); } int nfs_file_fsync(struct file *file, loff_t start, loff_t end, int datasync) { struct nfs_open_context *ctx = nfs_file_open_context(file); struct inode *inode = file_inode(file); int ret; trace_nfs_fsync_enter(inode); for (;;) { ret = file_write_and_wait_range(file, start, end); if (ret != 0) break; ret = nfs_file_fsync_commit(file, datasync); if (ret != 0) break; ret = pnfs_sync_inode(inode, !!datasync); if (ret != 0) break; if (!test_and_clear_bit(NFS_CONTEXT_RESEND_WRITES, &ctx->flags)) break; /* * 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; } trace_nfs_fsync_exit(inode, ret); return ret; } EXPORT_SYMBOL_GPL(nfs_file_fsync); /* * 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. * * Some pNFS layout drivers can only read/write at a certain block * granularity like all block devices and therefore we must perform * read/modify/write whenever a page hasn't read yet and the data * to be written there is not aligned to a block boundary and/or * smaller than the block size. * * 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 bool nfs_full_page_write(struct page *page, loff_t pos, unsigned int len) { unsigned int pglen = nfs_page_length(page); unsigned int offset = pos & (PAGE_SIZE - 1); unsigned int end = offset + len; return !pglen || (end >= pglen && !offset); } static bool nfs_want_read_modify_write(struct file *file, struct page *page, loff_t pos, unsigned int len) { /* * Up-to-date pages, those with ongoing or full-page write * don't need read/modify/write */ if (PageUptodate(page) || PagePrivate(page) || nfs_full_page_write(page, pos, len)) return false; if (pnfs_ld_read_whole_page(file->f_mapping->host)) return true; /* Open for reading too? */ if (file->f_mode & FMODE_READ) return true; return false; } /* * 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_SHIFT; struct page *page; int once_thru = 0; dfprintk(PAGECACHE, "NFS: write_begin(%pD2(%lu), %u@%lld)\n", file, mapping->host->i_ino, len, (long long) pos); start: 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); put_page(page); } else if (!once_thru && nfs_want_read_modify_write(file, page, pos, len)) { once_thru = 1; ret = nfs_readpage(file, page); put_page(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_SIZE - 1); struct nfs_open_context *ctx = nfs_file_open_context(file); int status; dfprintk(PAGECACHE, "NFS: write_end(%pD2(%lu), %u@%lld)\n", file, 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 + copied; if (pglen == 0) { zero_user_segments(page, 0, offset, end, PAGE_SIZE); SetPageUptodate(page); } else if (end >= pglen) { zero_user_segment(page, end, PAGE_SIZE); if (offset == 0) SetPageUptodate(page); } else zero_user_segment(page, pglen, PAGE_SIZE); } status = nfs_updatepage(file, page, offset, copied); unlock_page(page); put_page(page); if (status < 0) return status; NFS_I(mapping->host)->write_io += copied; if (nfs_ctx_key_to_expire(ctx, mapping->host)) { status = nfs_wb_all(mapping->host); if (status < 0) return status; } 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_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) { dfprintk(PAGECACHE, "NFS: release_page(%p)\n", page); /* 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 (atomic_read(&nfsi->commit_info.rpcs_out)) { *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); } static int nfs_swap_activate(struct swap_info_struct *sis, struct file *file, sector_t *span) { unsigned long blocks; long long isize; struct rpc_clnt *clnt = NFS_CLIENT(file->f_mapping->host); struct inode *inode = file->f_mapping->host; spin_lock(&inode->i_lock); blocks = inode->i_blocks; isize = inode->i_size; spin_unlock(&inode->i_lock); if (blocks*512 < isize) { pr_warn("swap activate: swapfile has holes\n"); return -EINVAL; } *span = sis->pages; return rpc_clnt_swap_activate(clnt); } static void nfs_swap_deactivate(struct file *file) { struct rpc_clnt *clnt = NFS_CLIENT(file->f_mapping->host); rpc_clnt_swap_deactivate(clnt); } 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, #ifdef CONFIG_MIGRATION .migratepage = nfs_migrate_page, #endif .launder_page = nfs_launder_page, .is_dirty_writeback = nfs_check_dirty_writeback, .error_remove_page = generic_error_remove_page, .swap_activate = nfs_swap_activate, .swap_deactivate = nfs_swap_deactivate, }; /* * 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 vm_fault_t nfs_vm_page_mkwrite(struct vm_fault *vmf) { struct page *page = vmf->page; struct file *filp = vmf->vma->vm_file; struct inode *inode = file_inode(filp); unsigned pagelen; vm_fault_t ret = VM_FAULT_NOPAGE; struct address_space *mapping; dfprintk(PAGECACHE, "NFS: vm_page_mkwrite(%pD2(%lu), offset %lld)\n", filp, filp->f_mapping->host->i_ino, (long long)page_offset(page)); sb_start_pagefault(inode->i_sb); /* make sure the cache has finished storing the page */ nfs_fscache_wait_on_page_write(NFS_I(inode), page); wait_on_bit_action(&NFS_I(inode)->flags, NFS_INO_INVALIDATING, nfs_wait_bit_killable, TASK_KILLABLE); lock_page(page); mapping = page_file_mapping(page); if (mapping != 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: sb_end_pagefault(inode->i_sb); return ret; } static const struct vm_operations_struct nfs_file_vm_ops = { .fault = filemap_fault, .map_pages = filemap_map_pages, .page_mkwrite = nfs_vm_page_mkwrite, }; static int nfs_need_check_write(struct file *filp, struct inode *inode, int error) { struct nfs_open_context *ctx; ctx = nfs_file_open_context(filp); if (nfs_error_is_fatal_on_server(error) || nfs_ctx_key_to_expire(ctx, inode)) return 1; return 0; } ssize_t nfs_file_write(struct kiocb *iocb, struct iov_iter *from) { struct file *file = iocb->ki_filp; struct inode *inode = file_inode(file); unsigned int mntflags = NFS_SERVER(inode)->flags; ssize_t result, written; errseq_t since; int error; result = nfs_key_timeout_notify(file, inode); if (result) return result; if (iocb->ki_flags & IOCB_DIRECT) return nfs_file_direct_write(iocb, from); dprintk("NFS: write(%pD2, %zu@%Ld)\n", file, iov_iter_count(from), (long long) iocb->ki_pos); if (IS_SWAPFILE(inode)) goto out_swapfile; /* * O_APPEND implies that we must revalidate the file length. */ if (iocb->ki_flags & IOCB_APPEND || iocb->ki_pos > i_size_read(inode)) { result = nfs_revalidate_file_size(inode, file); if (result) goto out; } nfs_clear_invalid_mapping(file->f_mapping); since = filemap_sample_wb_err(file->f_mapping); nfs_start_io_write(inode); result = generic_write_checks(iocb, from); if (result > 0) { current->backing_dev_info = inode_to_bdi(inode); result = generic_perform_write(file, from, iocb->ki_pos); current->backing_dev_info = NULL; } nfs_end_io_write(inode); if (result <= 0) goto out; written = result; iocb->ki_pos += written; if (mntflags & NFS_MOUNT_WRITE_EAGER) { result = filemap_fdatawrite_range(file->f_mapping, iocb->ki_pos - written, iocb->ki_pos - 1); if (result < 0) goto out; } if (mntflags & NFS_MOUNT_WRITE_WAIT) { result = filemap_fdatawait_range(file->f_mapping, iocb->ki_pos - written, iocb->ki_pos - 1); if (result < 0) goto out; } result = generic_write_sync(iocb, written); if (result < 0) goto out; /* Return error values */ error = filemap_check_wb_err(file->f_mapping, since); if (nfs_need_check_write(file, inode, error)) { int err = nfs_wb_all(inode); if (err < 0) result = err; } nfs_add_stats(inode, NFSIOS_NORMALWRITTENBYTES, written); out: return result; out_swapfile: printk(KERN_INFO "NFS: attempt to write to active swap file!\n"); return -ETXTBSY; } EXPORT_SYMBOL_GPL(nfs_file_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_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_wb_all(inode); l_ctx = nfs_get_lock_context(nfs_file_open_context(filp)); if (!IS_ERR(l_ctx)) { status = nfs_iocounter_wait(l_ctx); nfs_put_lock_context(l_ctx); /* NOTE: special case * If we're signalled while cleaning up locks on process exit, we * still need to complete the unlock. */ if (status < 0 && !(fl->fl_flags & FL_CLOSE)) return status; } /* * 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 = locks_lock_file_wait(filp, fl); return status; } 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 = locks_lock_file_wait(filp, fl); if (status < 0) goto out; /* * Invalidate cache to prevent missing any changes. If * the file is mapped, clear the page cache as well so * those mappings will be loaded. * * This makes locking act as a cache coherency point. */ nfs_sync_mapping(filp->f_mapping); if (!NFS_PROTO(inode)->have_delegation(inode, FMODE_READ)) { nfs_zap_caches(inode); if (mapping_mapped(filp->f_mapping)) nfs_revalidate_mapping(inode, filp->f_mapping); } 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(%pD2, t=%x, fl=%x, r=%lld:%lld)\n", filp, 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(%pD2, t=%x, fl=%x)\n", filp, 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 */ 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); const struct file_operations nfs_file_operations = { .llseek = nfs_file_llseek, .read_iter = nfs_file_read, .write_iter = 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 = generic_file_splice_read, .splice_write = iter_file_splice_write, .check_flags = nfs_check_flags, .setlease = simple_nosetlease, }; EXPORT_SYMBOL_GPL(nfs_file_operations);