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authorAmir Goldstein <amir73il@gmail.com>2018-08-29 08:41:29 +0300
committerMiklos Szeredi <mszeredi@redhat.com>2018-08-30 20:01:32 +0200
commit3d8f7615319b2bca87a4815e13787439e3339a93 (patch)
treef7f5c2be4f572892747e47c9fc1001e86f74ca61 /mm
parent45cd0faae3715e305bc46e23b34c5ed4d185ceb8 (diff)
downloadlinux-stericsson-3d8f7615319b2bca87a4815e13787439e3339a93.tar.gz
vfs: implement readahead(2) using POSIX_FADV_WILLNEED
The implementation of readahead(2) syscall is identical to that of fadvise64(POSIX_FADV_WILLNEED) with a few exceptions: 1. readahead(2) returns -EINVAL for !mapping->a_ops and fadvise64() ignores the request and returns 0. 2. fadvise64() checks for integer overflow corner case 3. fadvise64() calls the optional filesystem fadvise() file operation Unite the two implementations by calling vfs_fadvise() from readahead(2) syscall. Check the !mapping->a_ops in readahead(2) syscall to preserve documented syscall ABI behaviour. Suggested-by: Miklos Szeredi <mszeredi@redhat.com> Fixes: d1d04ef8572b ("ovl: stack file ops") Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Diffstat (limited to 'mm')
-rw-r--r--mm/Makefile3
-rw-r--r--mm/fadvise.c3
-rw-r--r--mm/readahead.c45
3 files changed, 21 insertions, 30 deletions
diff --git a/mm/Makefile b/mm/Makefile
index 8716bdabe1e6..26ef77a3883b 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -32,7 +32,7 @@ ifdef CONFIG_CROSS_MEMORY_ATTACH
mmu-$(CONFIG_MMU) += process_vm_access.o
endif
-obj-y := filemap.o mempool.o oom_kill.o \
+obj-y := filemap.o mempool.o oom_kill.o fadvise.o \
maccess.o page_alloc.o page-writeback.o \
readahead.o swap.o truncate.o vmscan.o shmem.o \
util.o mmzone.o vmstat.o backing-dev.o \
@@ -49,7 +49,6 @@ else
obj-y += bootmem.o
endif
-obj-$(CONFIG_ADVISE_SYSCALLS) += fadvise.o
ifdef CONFIG_MMU
obj-$(CONFIG_ADVISE_SYSCALLS) += madvise.o
endif
diff --git a/mm/fadvise.c b/mm/fadvise.c
index 2f59bac1cb77..467bcd032037 100644
--- a/mm/fadvise.c
+++ b/mm/fadvise.c
@@ -188,6 +188,8 @@ int vfs_fadvise(struct file *file, loff_t offset, loff_t len, int advice)
}
EXPORT_SYMBOL(vfs_fadvise);
+#ifdef CONFIG_ADVISE_SYSCALLS
+
int ksys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice)
{
struct fd f = fdget(fd);
@@ -215,3 +217,4 @@ SYSCALL_DEFINE4(fadvise64, int, fd, loff_t, offset, size_t, len, int, advice)
}
#endif
+#endif
diff --git a/mm/readahead.c b/mm/readahead.c
index a59ea70527b9..4e630143a0ba 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -20,6 +20,7 @@
#include <linux/file.h>
#include <linux/mm_inline.h>
#include <linux/blk-cgroup.h>
+#include <linux/fadvise.h>
#include "internal.h"
@@ -575,24 +576,6 @@ page_cache_async_readahead(struct address_space *mapping,
}
EXPORT_SYMBOL_GPL(page_cache_async_readahead);
-static ssize_t
-do_readahead(struct address_space *mapping, struct file *filp,
- pgoff_t index, unsigned long nr)
-{
- if (!mapping || !mapping->a_ops)
- return -EINVAL;
-
- /*
- * Readahead doesn't make sense for DAX inodes, but we don't want it
- * to report a failure either. Instead, we just return success and
- * don't do any work.
- */
- if (dax_mapping(mapping))
- return 0;
-
- return force_page_cache_readahead(mapping, filp, index, nr);
-}
-
ssize_t ksys_readahead(int fd, loff_t offset, size_t count)
{
ssize_t ret;
@@ -600,16 +583,22 @@ ssize_t ksys_readahead(int fd, loff_t offset, size_t count)
ret = -EBADF;
f = fdget(fd);
- if (f.file) {
- if (f.file->f_mode & FMODE_READ) {
- struct address_space *mapping = f.file->f_mapping;
- pgoff_t start = offset >> PAGE_SHIFT;
- pgoff_t end = (offset + count - 1) >> PAGE_SHIFT;
- unsigned long len = end - start + 1;
- ret = do_readahead(mapping, f.file, start, len);
- }
- fdput(f);
- }
+ if (!f.file || !(f.file->f_mode & FMODE_READ))
+ goto out;
+
+ /*
+ * The readahead() syscall is intended to run only on files
+ * that can execute readahead. If readahead is not possible
+ * on this file, then we must return -EINVAL.
+ */
+ ret = -EINVAL;
+ if (!f.file->f_mapping || !f.file->f_mapping->a_ops ||
+ !S_ISREG(file_inode(f.file)->i_mode))
+ goto out;
+
+ ret = vfs_fadvise(f.file, offset, count, POSIX_FADV_WILLNEED);
+out:
+ fdput(f);
return ret;
}