vfs: add the fadvise() file operation

This is going to be used by overlayfs and possibly useful
for other filesystems.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt
index ec2142c..a6c6a8a 100644 (file)
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -885,6 +885,7 @@ struct file_operations {
        ssize_t (*copy_file_range)(struct file *, loff_t, struct file *, loff_t, size_t, unsigned int);
        int (*clone_file_range)(struct file *, loff_t, struct file *, loff_t, u64);
        int (*dedupe_file_range)(struct file *, loff_t, struct file *, loff_t, u64);
+       int (*fadvise)(struct file *, loff_t, loff_t, int);
 };
 
 Again, all methods are called without any locks being held, unless
@@ -965,6 +966,8 @@ otherwise noted.
   dedupe_file_range: called by the ioctl(2) system call for FIDEDUPERANGE
        command.
 
+  fadvise: possibly called by the fadvise64() system call.
+
 Note that the file operations are implemented by the specific
 filesystem in which the inode resides. When opening a device node
 (character or block special) most filesystems will call special

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 3332270..6c0b4a1 100644 (file)
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1763,6 +1763,7 @@ struct file_operations {
                        u64);
        int (*dedupe_file_range)(struct file *, loff_t, struct file *, loff_t,
                        u64);
+       int (*fadvise)(struct file *, loff_t, loff_t, int);
 } __randomize_layout;
 
 struct inode_operations {
@@ -3459,4 +3460,8 @@ static inline bool dir_relax_shared(struct inode *inode)
 extern bool path_noexec(const struct path *path);
 extern void inode_nohighmem(struct inode *inode);
 
+/* mm/fadvise.c */
+extern int vfs_fadvise(struct file *file, loff_t offset, loff_t len,
+                      int advice);
+
 #endif /* _LINUX_FS_H */

diff --git a/mm/fadvise.c b/mm/fadvise.c
index 2d8376e..2f59bac 100644 (file)
--- a/mm/fadvise.c
+++ b/mm/fadvise.c
@@ -27,9 +27,9 @@
  * deactivate the pages and clear PG_Referenced.
  */
 
-int ksys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice)
+static int generic_fadvise(struct file *file, loff_t offset, loff_t len,
+                          int advice)
 {
-       struct fd f = fdget(fd);
        struct inode *inode;
        struct address_space *mapping;
        struct backing_dev_info *bdi;
@@ -37,22 +37,14 @@ int ksys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice)
        pgoff_t start_index;
        pgoff_t end_index;
        unsigned long nrpages;
-       int ret = 0;
 
-       if (!f.file)
-               return -EBADF;
+       inode = file_inode(file);
+       if (S_ISFIFO(inode->i_mode))
+               return -ESPIPE;
 
-       inode = file_inode(f.file);
-       if (S_ISFIFO(inode->i_mode)) {
-               ret = -ESPIPE;
-               goto out;
-       }
-
-       mapping = f.file->f_mapping;
-       if (!mapping || len < 0) {
-               ret = -EINVAL;
-               goto out;
-       }
+       mapping = file->f_mapping;
+       if (!mapping || len < 0)
+               return -EINVAL;
 
        bdi = inode_to_bdi(mapping->host);
 
@@ -67,9 +59,9 @@ int ksys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice)
                        /* no bad return value, but ignore advice */
                        break;
                default:
-                       ret = -EINVAL;
+                       return -EINVAL;
                }
-               goto out;
+               return 0;
        }
 
        /*
@@ -85,21 +77,21 @@ int ksys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice)
 
        switch (advice) {
        case POSIX_FADV_NORMAL:
-               f.file->f_ra.ra_pages = bdi->ra_pages;
-               spin_lock(&f.file->f_lock);
-               f.file->f_mode &= ~FMODE_RANDOM;
-               spin_unlock(&f.file->f_lock);
+               file->f_ra.ra_pages = bdi->ra_pages;
+               spin_lock(&file->f_lock);
+               file->f_mode &= ~FMODE_RANDOM;
+               spin_unlock(&file->f_lock);
                break;
        case POSIX_FADV_RANDOM:
-               spin_lock(&f.file->f_lock);
-               f.file->f_mode |= FMODE_RANDOM;
-               spin_unlock(&f.file->f_lock);
+               spin_lock(&file->f_lock);
+               file->f_mode |= FMODE_RANDOM;
+               spin_unlock(&file->f_lock);
                break;
        case POSIX_FADV_SEQUENTIAL:
-               f.file->f_ra.ra_pages = bdi->ra_pages * 2;
-               spin_lock(&f.file->f_lock);
-               f.file->f_mode &= ~FMODE_RANDOM;
-               spin_unlock(&f.file->f_lock);
+               file->f_ra.ra_pages = bdi->ra_pages * 2;
+               spin_lock(&file->f_lock);
+               file->f_mode &= ~FMODE_RANDOM;
+               spin_unlock(&file->f_lock);
                break;
        case POSIX_FADV_WILLNEED:
                /* First and last PARTIAL page! */
@@ -115,8 +107,7 @@ int ksys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice)
                 * Ignore return value because fadvise() shall return
                 * success even if filesystem can't retrieve a hint,
                 */
-               force_page_cache_readahead(mapping, f.file, start_index,
-                                          nrpages);
+               force_page_cache_readahead(mapping, file, start_index, nrpages);
                break;
        case POSIX_FADV_NOREUSE:
                break;
@@ -183,9 +174,30 @@ int ksys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice)
                }
                break;
        default:
-               ret = -EINVAL;
+               return -EINVAL;
        }
-out:
+       return 0;
+}
+
+int vfs_fadvise(struct file *file, loff_t offset, loff_t len, int advice)
+{
+       if (file->f_op->fadvise)
+               return file->f_op->fadvise(file, offset, len, advice);
+
+       return generic_fadvise(file, offset, len, advice);
+}
+EXPORT_SYMBOL(vfs_fadvise);
+
+int ksys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice)
+{
+       struct fd f = fdget(fd);
+       int ret;
+
+       if (!f.file)
+               return -EBADF;
+
+       ret = vfs_fadvise(f.file, offset, len, advice);
+
        fdput(f);
        return ret;
 }