Pfcache/API

Kernel pfcache API is described in linux/pfcache.h

Filesystem attributes

xattr "trusted.pfcache" (PFCACHE_XATTR_NAME)

for directories: "auto" -- checksum files at create, inherited from parent on mkdir.

for regular files: SHA-1 checksum, 40 (PFCACHE_CSUM_SIZE * 2) chars length hex string.

ioctls

FS_IOC_PFCACHE_OPEN

ioctl(fd, FS_IOC_PFCACHE_OPEN)

Try to reopen pfcache peer for this inode

Exit codes

-EPERM	no cap-sys-admin
-ENODATA	no checksum
-ENODEV	no prcache on fs
-ENOENT	cache peer not found
-EBUSY	already opened
-EINVAL	cache peer does not match or not regular file
-EMLINK	cache peer has itself cache peer, or symlinks mess
-ETXTBSY	cache peer opened for write
... plus all the open(2) error codes
0	success!

FS_IOC_PFCACHE_CLOSE

ioctl(fd, FS_IOC_PFCACHE_CLOSE)

Close pfcache peer for this inode inode

Exit codes

-EPERM	no cap-sys-admin
-ENOENT	not opened
0	success

FS_IOC_PFCACHE_DUMP

ioctl(fd, FS_IOC_PFCACHE_DUMP, struct pfcache_dump_request *)

Dump in-memory inodes for this fs, see linux/pfcache.h for description.

Exit codes

-EPERM	no cap-sys-admin
-EINVAL	-
-EINTR	-
>=0	Number of dumped inodes