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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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#include <linux/export.h>#include <linux/fs.h>#include <linux/mm.h>#include <linux/pagemap.h>#include <linux/slab.h>#include "internal.h"
/* * Grab a folio for writing and lock it. Attempt to allocate as large a folio * as possible to hold as much of the remaining length as possible in one go. */static struct folio *netfs_grab_folio_for_write(struct address_space *mapping, loff_t pos, size_t part){ pgoff_t index = pos / PAGE_SIZE; fgf_t fgp_flags = FGP_WRITEBEGIN;
if (mapping_large_folio_support(mapping)) fgp_flags |= fgf_set_order(pos % PAGE_SIZE + part);
return __filemap_get_folio(mapping, index, fgp_flags, mapping_gfp_mask(mapping));}
/* * Update i_size and estimate the update to i_blocks to reflect the additional * data written into the pagecache until we can find out from the server what * the values actually are. */void netfs_update_i_size(struct netfs_inode *ctx, struct inode *inode, loff_t pos, size_t copied){ loff_t i_size, end = pos + copied; blkcnt_t add; size_t gap;
if (end <= i_size_read(inode)) return;
if (ctx->ops->update_i_size) { ctx->ops->update_i_size(inode, end); return; }
spin_lock(&inode->i_lock);
i_size = i_size_read(inode); if (end > i_size) { i_size_write(inode, end);#if IS_ENABLED(CONFIG_FSCACHE) fscache_update_cookie(ctx->cache, NULL, &end);#endif
gap = SECTOR_SIZE - (i_size & (SECTOR_SIZE - 1)); if (copied > gap) { add = DIV_ROUND_UP(copied - gap, SECTOR_SIZE);
inode->i_blocks = min_t(blkcnt_t, DIV_ROUND_UP(end, SECTOR_SIZE), inode->i_blocks + add); } } spin_unlock(&inode->i_lock);}
/** * netfs_perform_write - Copy data into the pagecache. * @iocb: The operation parameters * @iter: The source buffer * @netfs_group: Grouping for dirty folios (eg. ceph snaps). * * Copy data into pagecache folios attached to the inode specified by @iocb. * The caller must hold appropriate inode locks. * * Dirty folios are tagged with a netfs_folio struct if they're not up to date * to indicate the range modified. Dirty folios may also be tagged with a * netfs-specific grouping such that data from an old group gets flushed before * a new one is started. */ssize_t netfs_perform_write(struct kiocb *iocb, struct iov_iter *iter, struct netfs_group *netfs_group){ struct file *file = iocb->ki_filp; struct inode *inode = file_inode(file); struct address_space *mapping = inode->i_mapping; struct netfs_inode *ctx = netfs_inode(inode); struct writeback_control wbc = { .sync_mode = WB_SYNC_NONE, .for_sync = true, .nr_to_write = LONG_MAX, .range_start = iocb->ki_pos, .range_end = iocb->ki_pos + iter->count, }; struct netfs_io_request *wreq = NULL; struct folio *folio = NULL, *writethrough = NULL; unsigned int bdp_flags = (iocb->ki_flags & IOCB_NOWAIT) ? BDP_ASYNC : 0; ssize_t written = 0, ret, ret2; loff_t pos = iocb->ki_pos; size_t max_chunk = mapping_max_folio_size(mapping); bool maybe_trouble = false;
if (unlikely(iocb->ki_flags & (IOCB_DSYNC | IOCB_SYNC)) ) { wbc_attach_fdatawrite_inode(&wbc, mapping->host);
ret = filemap_write_and_wait_range(mapping, pos, pos + iter->count); if (ret < 0) { wbc_detach_inode(&wbc); goto out; }
wreq = netfs_begin_writethrough(iocb, iter->count); if (IS_ERR(wreq)) { wbc_detach_inode(&wbc); ret = PTR_ERR(wreq); wreq = NULL; goto out; } if (!is_sync_kiocb(iocb)) wreq->iocb = iocb; netfs_stat(&netfs_n_wh_writethrough); } else { netfs_stat(&netfs_n_wh_buffered_write); }
do { enum netfs_folio_trace trace; struct netfs_folio *finfo; struct netfs_group *group; unsigned long long fpos; size_t flen; size_t offset; /* Offset into pagecache folio */ size_t part; /* Bytes to write to folio */ size_t copied; /* Bytes copied from user */ void *priv;
offset = pos & (max_chunk - 1); part = min(max_chunk - offset, iov_iter_count(iter));
/* Bring in the user pages that we will copy from _first_ lest * we hit a nasty deadlock on copying from the same page as * we're writing to, without it being marked uptodate. * * Not only is this an optimisation, but it is also required to * check that the address is actually valid, when atomic * usercopies are used below. * * We rely on the page being held onto long enough by the LRU * that we can grab it below if this causes it to be read. */ ret = -EFAULT; if (unlikely(fault_in_iov_iter_readable(iter, part) == part)) break;
folio = netfs_grab_folio_for_write(mapping, pos, part); if (IS_ERR(folio)) { ret = PTR_ERR(folio); break; }
flen = folio_size(folio); fpos = folio_pos(folio); offset = pos - fpos; part = min_t(size_t, flen - offset, part);
/* Wait for writeback to complete. The writeback engine owns * the info in folio->private and may change it until it * removes the WB mark. */ if (folio_get_private(folio) && folio_wait_writeback_killable(folio)) { ret = written ? -EINTR : -ERESTARTSYS; goto error_folio_unlock; }
if (signal_pending(current)) { ret = written ? -EINTR : -ERESTARTSYS; goto error_folio_unlock; }
finfo = netfs_folio_info(folio); group = netfs_folio_group(folio);
/* If the requested group differs from the group set on the * page, then we need to flush out the folio if it has a group * set (ie. is non-NULL). Note that COPY_TO_CACHE is a special * case, being a netfs annotation rather than an actual group. * * The filesystem isn't permitted to mix writes with groups and * writes without groups as the NULL group is used to indicate * that no group is set. */ if (unlikely(group != netfs_group) && group != NETFS_FOLIO_COPY_TO_CACHE && group) { WARN_ON_ONCE(!netfs_group); goto flush_content; }
/* Decide how we should modify a folio. We might be attempting * to do write-streaming, as we don't want to a local RMW cycle * if we can avoid it. If we're doing local caching or content * crypto, we award that priority over avoiding RMW. If the * file is open readably, then we let ->read_folio() fill in * the gaps. */ if (folio_test_uptodate(folio)) { if (mapping_writably_mapped(mapping)) flush_dcache_folio(folio); copied = copy_folio_from_iter_atomic(folio, offset, part, iter); if (unlikely(copied == 0)) goto copy_failed; trace = netfs_folio_is_uptodate; goto copied_uptodate; }
/* If the page is above the zero-point then we assume that the * server would just return a block of zeros or a short read if * we try to read it. */ if (fpos >= netfs_read_zero_point(inode)) { folio_zero_segment(folio, 0, offset); copied = copy_folio_from_iter_atomic(folio, offset, part, iter); if (unlikely(copied == 0)) goto copy_failed; folio_zero_segment(folio, offset + copied, flen); if (finfo) trace = netfs_modify_and_clear_rm_finfo; else trace = netfs_modify_and_clear; goto mark_uptodate; }
/* See if we can write a whole folio in one go. */ if (!maybe_trouble && offset == 0 && part >= flen) { copied = copy_folio_from_iter_atomic(folio, offset, part, iter); if (likely(copied == part)) { if (finfo) trace = netfs_whole_folio_modify_filled; else trace = netfs_whole_folio_modify; goto mark_uptodate; } if (copied == 0) goto copy_failed; if (!finfo || copied <= finfo->dirty_offset) { maybe_trouble = true; iov_iter_revert(iter, copied); copied = 0; folio_unlock(folio); goto retry; }
/* We overwrote some existing dirty data, so we have to * accept the partial write. */ finfo->dirty_len += finfo->dirty_offset; if (finfo->dirty_len == flen) { trace = netfs_whole_folio_modify_filled_efault; goto mark_uptodate; } if (copied > finfo->dirty_len) finfo->dirty_len = copied; finfo->dirty_offset = 0; trace = netfs_whole_folio_modify_efault; goto copied; }
/* We don't want to do a streaming write on a file that loses * caching service temporarily because the backing store got * culled. */ if (netfs_is_cache_maybe_enabled(ctx)) { if (finfo) { netfs_stat(&netfs_n_wh_wstream_conflict); goto flush_content; } ret = netfs_prefetch_for_write(file, folio, offset, part); if (ret < 0) { _debug("prefetch = %zd", ret); goto error_folio_unlock; } /* Note that copy-to-cache may have been set. */
copied = copy_folio_from_iter_atomic(folio, offset, part, iter); if (unlikely(copied == 0)) goto copy_failed; trace = netfs_just_prefetch; goto copied_uptodate; }
/* Do a streaming write on a folio that has nothing in it yet. */ if (!finfo) { ret = -EIO; if (WARN_ON(folio_get_private(folio))) goto error_folio_unlock; copied = copy_folio_from_iter_atomic(folio, offset, part, iter); if (unlikely(copied == 0)) goto copy_failed; if (offset == 0 && copied == flen) { trace = netfs_streaming_filled_page; goto mark_uptodate; }
finfo = kzalloc_obj(*finfo); if (!finfo) { iov_iter_revert(iter, copied); ret = -ENOMEM; goto error_folio_unlock; } finfo->netfs_group = netfs_get_group(netfs_group); finfo->dirty_offset = offset; finfo->dirty_len = copied; folio_attach_private(folio, (void *)((unsigned long)finfo | NETFS_FOLIO_INFO)); trace = netfs_streaming_write; goto copied; }
/* We can continue a streaming write only if it continues on * from the previous. If it overlaps, we must flush lest we * suffer a partial copy and disjoint dirty regions. */ if (offset == finfo->dirty_offset + finfo->dirty_len) { copied = copy_folio_from_iter_atomic(folio, offset, part, iter); if (unlikely(copied == 0)) goto copy_failed; finfo->dirty_len += copied; if (finfo->dirty_offset == 0 && finfo->dirty_len == flen) { trace = netfs_streaming_cont_filled_page; goto mark_uptodate; } trace = netfs_streaming_write_cont; goto copied; }
/* Incompatible write; flush the folio and try again. */ flush_content: trace_netfs_folio(folio, netfs_flush_content); folio_unlock(folio); folio_put(folio); ret = filemap_write_and_wait_range(mapping, fpos, fpos + flen - 1); if (ret < 0) goto out; continue;
/* Mark a folio as being up to data when we've filled it * completely. If the folio has a group attached, then it must * be the same group, otherwise we should have flushed it out * above. We have to get rid of the netfs_folio struct if * there was one. */ mark_uptodate: folio_mark_uptodate(folio);
copied_uptodate: priv = folio_get_private(folio); if (likely(priv == netfs_group)) { /* Already set correctly; no change required. */ } else if (priv == NETFS_FOLIO_COPY_TO_CACHE) { if (!netfs_group) folio_detach_private(folio); else folio_change_private(folio, netfs_get_group(netfs_group)); } else if (!priv) { folio_attach_private(folio, netfs_get_group(netfs_group)); } else { WARN_ON_ONCE(!finfo); if (netfs_group) /* finfo->netfs_group has a ref */ folio_change_private(folio, netfs_group); else folio_detach_private(folio); kfree(finfo); }
copied: trace_netfs_folio(folio, trace); flush_dcache_folio(folio);
/* Update the inode size if we moved the EOF marker */ netfs_update_i_size(ctx, inode, pos, copied); pos += copied; written += copied;
if (likely(!wreq)) { folio_mark_dirty(folio); folio_unlock(folio); } else { netfs_advance_writethrough(wreq, &wbc, folio, copied, offset + copied == flen, &writethrough); /* Folio unlocked */ } retry: folio_put(folio); folio = NULL;
ret = balance_dirty_pages_ratelimited_flags(mapping, bdp_flags); if (unlikely(ret < 0)) break;
cond_resched(); } while (iov_iter_count(iter));
out: if (likely(written)) { /* Set indication that ctime and mtime got updated in case * close is deferred. */ set_bit(NETFS_ICTX_MODIFIED_ATTR, &ctx->flags); if (unlikely(ctx->ops->post_modify)) ctx->ops->post_modify(inode); }
if (unlikely(wreq)) { ret2 = netfs_end_writethrough(wreq, &wbc, writethrough); wbc_detach_inode(&wbc); if (ret2 == -EIOCBQUEUED) return ret2; if (ret == 0 && ret2 < 0) ret = ret2; }
iocb->ki_pos += written; _leave(" = %zd [%zd]", written, ret); return written ? written : ret;
copy_failed: ret = -EFAULT;error_folio_unlock: folio_unlock(folio); folio_put(folio); goto out;}EXPORT_SYMBOL(netfs_perform_write);
/** * netfs_buffered_write_iter_locked - write data to a file * @iocb: IO state structure (file, offset, etc.) * @from: iov_iter with data to write * @netfs_group: Grouping for dirty folios (eg. ceph snaps). * * This function does all the work needed for actually writing data to a * file. It does all basic checks, removes SUID from the file, updates * modification times and calls proper subroutines depending on whether we * do direct IO or a standard buffered write. * * The caller must hold appropriate locks around this function and have called * generic_write_checks() already. The caller is also responsible for doing * any necessary syncing afterwards. * * This function does *not* take care of syncing data in case of O_SYNC write. * A caller has to handle it. This is mainly due to the fact that we want to * avoid syncing under i_rwsem. * * Return: * * number of bytes written, even for truncated writes * * negative error code if no data has been written at all */ssize_t netfs_buffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *from, struct netfs_group *netfs_group){ struct file *file = iocb->ki_filp; ssize_t ret;
trace_netfs_write_iter(iocb, from);
ret = file_remove_privs(file); if (ret) return ret;
ret = file_update_time(file); if (ret) return ret;
return netfs_perform_write(iocb, from, netfs_group);}EXPORT_SYMBOL(netfs_buffered_write_iter_locked);
/** * netfs_file_write_iter - write data to a file * @iocb: IO state structure * @from: iov_iter with data to write * * Perform a write to a file, writing into the pagecache if possible and doing * an unbuffered write instead if not. * * Return: * * Negative error code if no data has been written at all of * vfs_fsync_range() failed for a synchronous write * * Number of bytes written, even for truncated writes */ssize_t netfs_file_write_iter(struct kiocb *iocb, struct iov_iter *from){ struct file *file = iocb->ki_filp; struct inode *inode = file->f_mapping->host; struct netfs_inode *ictx = netfs_inode(inode); ssize_t ret;
_enter("%llx,%zx,%llx", iocb->ki_pos, iov_iter_count(from), i_size_read(inode));
if (!iov_iter_count(from)) return 0;
if ((iocb->ki_flags & IOCB_DIRECT) || test_bit(NETFS_ICTX_UNBUFFERED, &ictx->flags)) return netfs_unbuffered_write_iter(iocb, from);
ret = netfs_start_io_write(inode); if (ret < 0) return ret;
ret = generic_write_checks(iocb, from); if (ret > 0) ret = netfs_buffered_write_iter_locked(iocb, from, NULL); netfs_end_io_write(inode); if (ret > 0) ret = generic_write_sync(iocb, ret); return ret;}EXPORT_SYMBOL(netfs_file_write_iter);
/* * Notification that a previously read-only page is about to become writable. * The caller indicates the precise page that needs to be written to, but * we only track group on a per-folio basis, so we block more often than * we might otherwise. */vm_fault_t netfs_page_mkwrite(struct vm_fault *vmf, struct netfs_group *netfs_group){ struct netfs_group *group; struct folio *folio = page_folio(vmf->page); struct file *file = vmf->vma->vm_file; struct address_space *mapping = file->f_mapping; struct inode *inode = file_inode(file); struct netfs_inode *ictx = netfs_inode(inode); vm_fault_t ret = VM_FAULT_NOPAGE; void *priv; int err;
_enter("%lx", folio->index);
sb_start_pagefault(inode->i_sb);
if (folio_lock_killable(folio) < 0) goto out; if (folio->mapping != mapping) goto unlock; if (folio_wait_writeback_killable(folio) < 0) goto unlock;
/* Can we see a streaming write here? */ if (WARN_ON(!folio_test_uptodate(folio))) { ret = VM_FAULT_SIGBUS; goto unlock; }
group = netfs_folio_group(folio); if (group && group != netfs_group && group != NETFS_FOLIO_COPY_TO_CACHE) { folio_unlock(folio); err = filemap_fdatawrite_range(mapping, folio_pos(folio), folio_next_pos(folio)); switch (err) { case 0: ret = VM_FAULT_RETRY; goto out; case -ENOMEM: ret = VM_FAULT_OOM; goto out; default: ret = VM_FAULT_SIGBUS; goto out; } }
if (folio_test_dirty(folio)) trace_netfs_folio(folio, netfs_folio_trace_mkwrite_plus); else trace_netfs_folio(folio, netfs_folio_trace_mkwrite);
priv = folio_get_private(folio); if (priv != netfs_group) { if (!netfs_group && priv == NETFS_FOLIO_COPY_TO_CACHE) folio_detach_private(folio); else if (netfs_group && priv == NETFS_FOLIO_COPY_TO_CACHE) folio_change_private(folio, netfs_get_group(netfs_group)); else if (netfs_group && !priv) folio_attach_private(folio, netfs_get_group(netfs_group)); else WARN_ON_ONCE(1); }
file_update_time(file); set_bit(NETFS_ICTX_MODIFIED_ATTR, &ictx->flags); if (ictx->ops->post_modify) ictx->ops->post_modify(inode); ret = VM_FAULT_LOCKED;out: sb_end_pagefault(inode->i_sb); return ret;unlock: folio_unlock(folio); goto out;}EXPORT_SYMBOL(netfs_page_mkwrite);