Revert "fanotify: disable readahead if we have pre-content watches"

This reverts commit fac84846a28c0950d4433118b3dffd44306df62d.

Signed-off-by: Amir Goldstein <[e-mail]>
Signed-off-by: Jan Kara <[e-mail]>
Link: https://patch.msgid.link/[e-mail]

mm/filemap.c

···
 	unsigned long vm_flags = vmf->vma->vm_flags;
 	unsigned int mmap_miss;
 
-	/*
-	 * If we have pre-content watches we need to disable readahead to make
-	 * sure that we don't populate our mapping with 0 filled pages that we
-	 * never emitted an event for.
-	 */
-	if (unlikely(FMODE_FSNOTIFY_HSM(file->f_mode)))
-		return fpin;
-
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 	/* Use the readahead code, even if readahead is disabled */
 	if ((vm_flags & VM_HUGEPAGE) && HPAGE_PMD_ORDER <= MAX_PAGECACHE_ORDER) {
···
 	DEFINE_READAHEAD(ractl, file, ra, file->f_mapping, vmf->pgoff);
 	struct file *fpin = NULL;
 	unsigned int mmap_miss;
-
-	/* See comment in do_sync_mmap_readahead. */
-	if (unlikely(FMODE_FSNOTIFY_HSM(file->f_mode)))
-		return fpin;
 
 	/* If we don't want any read-ahead, don't bother */
 	if (vmf->vma->vm_flags & VM_RAND_READ || !ra->ra_pages)

mm/readahead.c

···
 #include <linux/blk-cgroup.h>
 #include <linux/fadvise.h>
 #include <linux/sched/mm.h>
-#include <linux/fsnotify.h>
 
 #include "internal.h"
 
···
 	pgoff_t prev_index, miss;
 
 	/*
-	 * If we have pre-content watches we need to disable readahead to make
-	 * sure that we don't find 0 filled pages in cache that we never emitted
-	 * events for. Filesystems supporting HSM must make sure to not call
-	 * this function with ractl->file unset for files handled by HSM.
-	 */
-	if (ractl->file && unlikely(FMODE_FSNOTIFY_HSM(ractl->file->f_mode)))
-		return;
-
-	/*
 	 * Even if readahead is disabled, issue this request as readahead
 	 * as we'll need it to satisfy the requested range. The forced
 	 * readahead will do the right thing and limit the read to just the
···
 
 	/* no readahead */
 	if (!ra->ra_pages)
-		return;
-
-	/* See the comment in page_cache_sync_ra. */
-	if (ractl->file && unlikely(FMODE_FSNOTIFY_HSM(ractl->file->f_mode)))
 		return;
 
 	/*