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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>
This commit is contained in:
Amir Goldstein 2018-08-27 15:56:02 +03:00 committed by Miklos Szeredi
parent 17ef445f9b
commit 45cd0faae3
3 changed files with 53 additions and 33 deletions
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3
Documentation/filesystems/vfs.txt
View File

@ -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

5
include/linux/fs.h
View File

@ -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 */

78
mm/fadvise.c
View File

@ -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;
}