[v2] mm: shmem: implement POSIX_FADV_[WILL|DONT]NEED for shmem

Message ID	1638442253-1591-1-git-send-email-quic_charante@quicinc.com (mailing list archive)
State	New
Headers	show Return-Path: <owner-linux-mm@kvack.org> Date: Subject: Cc: To: From: Sender; bh=HIGcD/jaqNClG+MM4DCw3sUIoBAVcod6MlDO/qs3diw=; b=YcEkCp470mxL0YPoTjSoJPK/mAVVNd/w3LbecnZTfwppokG0OZb+W0uL2I95p9HnO2FN7/wI 1VKWlmYG80pO90ALIDe+pSsNQyn8Z2YaksC52rzHm613EUtNmnBsCMZYdgUTaYgaJtUcvtTY IItRTQ82poThcDfN8yOqSIqvXUE= sender: charante) by smtp.codeaurora.org (Postfix) with ESMTPSA id 21A62C4338F; Thu, 2 Dec 2021 10:51:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 smtp.codeaurora.org 21A62C4338F From: Charan Teja Reddy <quic_charante@quicinc.com> To: hughd@google.com, akpm@linux-foundation.org, vbabka@suse.cz, rientjes@google.com, david@redhat.com, mhocko@suse.com, surenb@google.com, linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, Charan Teja Reddy <charante@codeaurora.org> Subject: [PATCH v2] mm: shmem: implement POSIX_FADV_[WILL\|DONT]NEED for shmem Date: Thu, 2 Dec 2021 16:20:53 +0530 Message-Id: <1638442253-1591-1-git-send-email-quic_charante@quicinc.com> Sender: owner-linux-mm@kvack.org Precedence: bulk
Series	[v2] mm: shmem: implement POSIX_FADV_[WILL\|DONT]NEED for shmem \| expand [v2] mm: shmem: implement POSIX_FADV_[WILL\|DONT]NEED for shmem

diff --git a/mm/shmem.c b/mm/shmem.c index 70d9ce2..4c4685f 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -38,6 +38,8 @@ #include <linux/hugetlb.h> #include <linux/frontswap.h> #include <linux/fs_parser.h> +#include <linux/mm_inline.h> +#include <linux/fadvise.h> #include <asm/tlbflush.h> /* for arch/microblaze update_mmu_cache() */ @@ -2792,6 +2794,170 @@ static long shmem_fallocate(struct file *file, int mode, loff_t offset, return error; } +static void shmem_isolate_pages_range(struct address_space *mapping, loff_t start, + loff_t end, struct list_head *list) +{ + XA_STATE(xas, &mapping->i_pages, start); + struct page *page; + + rcu_read_lock(); + xas_for_each(&xas, page, end) { + if (xas_retry(&xas, page)) + continue; + if (xa_is_value(page)) + continue; + if (!get_page_unless_zero(page)) + continue; + if (isolate_lru_page(page)) + continue; + + list_add(&page->lru, list); + inc_node_page_state(page, NR_ISOLATED_ANON + + page_is_file_lru(page)); + put_page(page); + if (need_resched()) { + xas_pause(&xas); + cond_resched_rcu(); + } + } + rcu_read_unlock(); +} + +static int shmem_fadvise_dontneed(struct address_space *mapping, loff_t start, + loff_t end) +{ + int ret; + struct page *page; + LIST_HEAD(list); + + if (!shmem_mapping(mapping)) + return -EINVAL; + + if (!total_swap_pages) + return 0; + + lru_add_drain(); + shmem_isolate_pages_range(mapping, start, end, &list); + + while (!list_empty(&list)) { + page = lru_to_page(&list); + list_del(&page->lru); + lock_page(page); + if (clear_page_dirty_for_io(page)) { + struct writeback_control wbc = { + .sync_mode = WB_SYNC_NONE, + .nr_to_write = LONG_MAX, + .range_start = 0, + .range_end = LLONG_MAX, + .for_reclaim = 1, + }; + + SetPageReclaim(page); + ret = shmem_writepage(page, &wbc); + if (ret || PageWriteback(page)) { + if (ret) + unlock_page(page); + putback_lru_page(page); + dec_node_page_state(page, NR_ISOLATED_ANON + + page_is_file_lru(page)); + continue; + } + } + + if (!PageWriteback(page)) + ClearPageReclaim(page); + + /* + * shmem_writepage() place the page in the swapcache. + * Delete the page from the swapcache and release the + * page. + */ + dec_node_page_state(page, NR_ISOLATED_ANON + + page_is_file_lru(page)); + lock_page(page); + delete_from_swap_cache(page); + unlock_page(page); + put_page(page); + + } + + return 0; +} + +static int shmem_fadvise_willneed(struct address_space *mapping, + pgoff_t start, pgoff_t long end) +{ + XA_STATE(xas, &mapping->i_pages, start); + struct page *page; + + rcu_read_lock(); + page = xas_find(&xas, end); + rcu_read_unlock(); + + while (page) { + if (xa_is_value(page)) { + page = shmem_read_mapping_page(mapping, xas.xa_index); + if (!IS_ERR(page)) + put_page(page); + } + + if (need_resched()) { + xas_pause(&xas); + cond_resched(); + } + + rcu_read_lock(); + page = xas_next_entry(&xas, end); + rcu_read_unlock(); + } + + return 0; +} + +static int shmem_fadvise(struct file *file, loff_t offset, loff_t len, int advice) +{ + loff_t endbyte; + pgoff_t start_index; + pgoff_t end_index; + struct address_space *mapping; + int ret = 0; + + mapping = file->f_mapping; + if (!mapping || len < 0) + return -EINVAL; + + endbyte = (u64)offset + (u64)len; + if (!len || endbyte < len) + endbyte = -1; + else + endbyte--; + + + start_index = offset >> PAGE_SHIFT; + end_index = endbyte >> PAGE_SHIFT; + switch (advice) { + case POSIX_FADV_DONTNEED: + ret = shmem_fadvise_dontneed(mapping, start_index, end_index); + break; + case POSIX_FADV_WILLNEED: + ret = shmem_fadvise_willneed(mapping, start_index, end_index); + break; + case POSIX_FADV_NORMAL: + case POSIX_FADV_RANDOM: + case POSIX_FADV_SEQUENTIAL: + case POSIX_FADV_NOREUSE: + /* + * No bad return value, but ignore advice. May have to + * implement in future. + */ + break; + default: + return -EINVAL; + } + + return ret; +} + static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf) { struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb); @@ -3799,6 +3965,7 @@ static const struct file_operations shmem_file_operations = { .splice_write = iter_file_splice_write, .fallocate = shmem_fallocate, #endif + .fadvise = shmem_fadvise, }; static const struct inode_operations shmem_inode_operations = {

[v2] mm: shmem: implement POSIX_FADV_[WILL|DONT]NEED for shmem

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