The patch titled
Subject: tmpfs: support SEEK_DATA and SEEK_HOLE
has been added to the -mm tree. Its filename is
tmpfs-support-seek_data-and-seek_hole.patch
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------------------------------------------------------
From: Hugh Dickins <hughd@xxxxxxxxxx>
Subject: tmpfs: support SEEK_DATA and SEEK_HOLE
It's quite easy for tmpfs to scan the radix_tree to support llseek's new
SEEK_DATA and SEEK_HOLE options: so add them while the minutiae are still
on my mind (in particular, the !PageUptodate-ness of pages fallocated but
still unwritten).
But I don't know who actually uses SEEK_DATA or SEEK_HOLE, and whether it
would be of any use to them on tmpfs. This code adds 92 lines and 752
bytes on x86_64 - is that bloat or worthwhile?
Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Cc: Josef Bacik <josef@xxxxxxxxxx>
Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>
Cc: Andreas Dilger <adilger@xxxxxxxxx>
Cc: Dave Chinner <david@xxxxxxxxxxxxx>
Cc: Marco Stornelli <marco.stornelli@xxxxxxxxx>
Cc: Jeff liu <jeff.liu@xxxxxxxxxx>
Cc: Chris Mason <chris.mason@xxxxxxxxxx>
Cc: Sunil Mushran <sunil.mushran@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/shmem.c | 94 ++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 93 insertions(+), 1 deletion(-)
diff -puN mm/shmem.c~tmpfs-support-seek_data-and-seek_hole mm/shmem.c
--- a/mm/shmem.c~tmpfs-support-seek_data-and-seek_hole
+++ a/mm/shmem.c
@@ -439,6 +439,56 @@ void shmem_unlock_mapping(struct address
}
/*
+ * llseek SEEK_DATA or SEEK_HOLE through the radix_tree.
+ */
+static pgoff_t shmem_seek_hole_data(struct address_space *mapping,
+ pgoff_t index, pgoff_t end, int origin)
+{
+ struct page *page;
+ struct pagevec pvec;
+ pgoff_t indices[PAGEVEC_SIZE];
+ bool done = false;
+ int i;
+
+ pagevec_init(&pvec, 0);
+ pvec.nr = 1; /* start small: we may be there already */
+ while (!done) {
+ pvec.nr = shmem_find_get_pages_and_swap(mapping, index,
+ pvec.nr, pvec.pages, indices);
+ if (!pvec.nr) {
+ if (origin == SEEK_DATA)
+ index = end;
+ break;
+ }
+ for (i = 0; i < pvec.nr; i++, index++) {
+ if (index < indices[i]) {
+ if (origin == SEEK_HOLE) {
+ done = true;
+ break;
+ }
+ index = indices[i];
+ }
+ page = pvec.pages[i];
+ if (page && !radix_tree_exceptional_entry(page)) {
+ if (!PageUptodate(page))
+ page = NULL;
+ }
+ if (index >= end ||
+ (page && origin == SEEK_DATA) ||
+ (!page && origin == SEEK_HOLE)) {
+ done = true;
+ break;
+ }
+ }
+ shmem_deswap_pagevec(&pvec);
+ pagevec_release(&pvec);
+ pvec.nr = PAGEVEC_SIZE;
+ cond_resched();
+ }
+ return index;
+}
+
+/*
* Remove range of pages and swap entries from radix tree, and free them.
* If !unfalloc, truncate or punch hole; if unfalloc, undo failed fallocate.
*/
@@ -1674,6 +1724,48 @@ static ssize_t shmem_file_splice_read(st
return error;
}
+static loff_t shmem_file_llseek(struct file *file, loff_t offset, int origin)
+{
+ struct address_space *mapping;
+ struct inode *inode;
+ pgoff_t start, end;
+ loff_t new_offset;
+
+ if (origin != SEEK_DATA && origin != SEEK_HOLE)
+ return generic_file_llseek_size(file, offset, origin,
+ MAX_LFS_FILESIZE);
+ mapping = file->f_mapping;
+ inode = mapping->host;
+ mutex_lock(&inode->i_mutex);
+ /* We're holding i_mutex so we can access i_size directly */
+
+ if (offset < 0)
+ offset = -EINVAL;
+ else if (offset >= inode->i_size)
+ offset = -ENXIO;
+ else {
+ start = offset >> PAGE_CACHE_SHIFT;
+ end = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+ new_offset = shmem_seek_hole_data(mapping, start, end, origin);
+ new_offset <<= PAGE_CACHE_SHIFT;
+ if (new_offset > offset) {
+ if (new_offset < inode->i_size)
+ offset = new_offset;
+ else if (origin == SEEK_DATA)
+ offset = -ENXIO;
+ else
+ offset = inode->i_size;
+ }
+ }
+
+ if (offset >= 0 && offset != file->f_pos) {
+ file->f_pos = offset;
+ file->f_version = 0;
+ }
+ mutex_unlock(&inode->i_mutex);
+ return offset;
+}
+
static long shmem_fallocate(struct file *file, int mode, loff_t offset,
loff_t len)
{
@@ -2667,7 +2759,7 @@ static const struct address_space_operat
static const struct file_operations shmem_file_operations = {
.mmap = shmem_mmap,
#ifdef CONFIG_TMPFS
- .llseek = generic_file_llseek,
+ .llseek = shmem_file_llseek,
.read = do_sync_read,
.write = do_sync_write,
.aio_read = shmem_file_aio_read,
_
Subject: Subject: tmpfs: support SEEK_DATA and SEEK_HOLE
Patches currently in -mm which might be from hughd@xxxxxxxxxx are
linux-next.patch
mm-remove-swap-token-code.patch
mm-vmscan-remove-lumpy-reclaim.patch
mm-vmscan-do-not-stall-on-writeback-during-memory-compaction.patch
mm-vmscan-remove-reclaim_mode_t.patch
mm-mmapc-find_vma-remove-unnecessary-ifmm-check.patch
mm-mmapc-find_vma-remove-unnecessary-ifmm-check-fix.patch
mm-fork-fix-overflow-in-vma-length-when-copying-mmap-on-clone.patch
mm-correctly-synchronize-rss-counters-at-exit-exec.patch
bug-introduce-build_bug_on_invalid-macro.patch
bug-completely-remove-code-generated-by-disabled-vm_bug_on.patch
shmem-replace-page-if-mapping-excludes-its-zone.patch
tmpfs-enable-nosec-optimization.patch
tmpfs-optimize-clearing-when-writing.patch
tmpfs-support-fallocate-falloc_fl_punch_hole.patch
mm-fs-route-madv_remove-to-falloc_fl_punch_hole.patch
mm-fs-remove-truncate_range.patch
tmpfs-support-fallocate-preallocation.patch
tmpfs-undo-fallocation-on-failure.patch
tmpfs-quit-when-fallocate-fills-memory.patch
tmpfs-support-seek_data-and-seek_hole.patch
memcg-fix-change-behavior-of-shared-anon-at-moving-task.patch
memcg-swap-mem_cgroup_move_swap_account-never-needs-fixup.patch
memcg-swap-use-mem_cgroup_uncharge_swap.patch
mm-memcg-scanning_global_lru-means-mem_cgroup_disabled.patch
mm-memcg-move-reclaim_stat-into-lruvec.patch
mm-push-lru-index-into-shrink_active_list.patch
mm-push-lru-index-into-shrink_active_list-fix.patch
mm-mark-mm-inline-functions-as-__always_inline.patch
mm-remove-lru-type-checks-from-__isolate_lru_page.patch
mm-memcg-kill-mem_cgroup_lru_del.patch
mm-memcg-use-vm_swappiness-from-target-memory-cgroup.patch
memcg-add-mlock-statistic-in-memorystat.patch
memcg-add-mlock-statistic-in-memorystat-fix.patch
mm-vmscan-store-priority-in-struct-scan_control.patch
mm-add-link-from-struct-lruvec-to-struct-zone.patch
mm-vmscan-push-lruvec-pointer-into-isolate_lru_pages.patch
mm-vmscan-push-zone-pointer-into-shrink_page_list.patch
mm-vmscan-remove-update_isolated_counts.patch
mm-vmscan-push-lruvec-pointer-into-putback_inactive_pages.patch
mm-vmscan-replace-zone_nr_lru_pages-with-get_lruvec_size.patch
mm-vmscan-push-lruvec-pointer-into-inactive_list_is_low.patch
mm-vmscan-push-lruvec-pointer-into-shrink_list.patch
mm-vmscan-push-lruvec-pointer-into-get_scan_count.patch
mm-vmscan-push-lruvec-pointer-into-should_continue_reclaim.patch
mm-vmscan-kill-struct-mem_cgroup_zone.patch
mm-huge_memoryc-use-lockdep_assert_held.patch
proc-clean-up-proc-pid-environ-handling.patch
proc-remove-mm_for_maps.patch
proc-use-mm_access-instead-of-ptrace_may_access.patch
proc-report-file-anon-bit-in-proc-pid-pagemap.patch
proc-use-is_err_or_null.patch
fork-call-complete_vfork_done-after-clearing-child_tid-and-flushing-rss-counters.patch
prio_tree-debugging-patch.patch
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