| Message ID | 1497544930-19174-6-git-send-email-axboe@kernel.dk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Jens, > We have a pwritev2(2) interface based on passing in flags. Add an > fcntl interface for querying these flags, and also for setting them > as well: > > F_GET_WRITE_LIFE Returns one of the valid type of write hints, > like WRITE_HINT_MEDIUM. > > F_SET_WRITE_LIFE Pass in a WRITE_HINT_* type to set the > write life time hint for this file/inode. > Returns 0 on succes, -1 otherwise. It seems like an overkill to have different fcntls for different hints. And since we are expecting more, maybe these should be F_{GET,SET}_HINT and then the individual flags can be WRITE_LIFETIME_FOOBAR? Otherwise OK with the fnctl approach.
On 06/16/2017 10:44 AM, Martin K. Petersen wrote: > > Jens, > >> We have a pwritev2(2) interface based on passing in flags. Add an >> fcntl interface for querying these flags, and also for setting them >> as well: >> >> F_GET_WRITE_LIFE Returns one of the valid type of write hints, >> like WRITE_HINT_MEDIUM. >> >> F_SET_WRITE_LIFE Pass in a WRITE_HINT_* type to set the >> write life time hint for this file/inode. >> Returns 0 on succes, -1 otherwise. > > It seems like an overkill to have different fcntls for different > hints. And since we are expecting more, maybe these should be > F_{GET,SET}_HINT and then the individual flags can be > WRITE_LIFETIME_FOOBAR? > > Otherwise OK with the fnctl approach. OK, that's a useful suggestion. The hints are already of the WRITE_HINT_* variant, so I don't think we need to change that. I'll change the name.
On Fri, Jun 16, 2017 at 12:44:09PM -0400, Martin K. Petersen wrote: > It seems like an overkill to have different fcntls for different > hints. And since we are expecting more, maybe these should be > F_{GET,SET}_HINT and then the individual flags can be > WRITE_LIFETIME_FOOBAR? That's what I was trying to explain earlier - have F_{GET,SET}_HINT ake a u16 (or maybe even a u32 or u64 with the remainder reserved) and then take 3 bits for the write lifetime. Which btw means we'd have another 3 possible values left if we encode is as a value instead of as bits.
diff --git a/fs/fcntl.c b/fs/fcntl.c index f4e7267d117f..f89fef847f73 100644 --- a/fs/fcntl.c +++ b/fs/fcntl.c @@ -243,6 +243,40 @@ static int f_getowner_uids(struct file *filp, unsigned long arg) } #endif +long fcntl_write_life(struct file *file, unsigned int cmd, unsigned long arg) +{ + struct inode *inode = file_inode(file); + long ret; + + switch (cmd) { + case F_GET_WRITE_LIFE: + ret = mask_to_write_hint(inode->i_flags, S_WRITE_LIFE_SHIFT); + break; + case F_SET_WRITE_LIFE: { + enum write_hint hint = arg; + + switch (hint) { + case WRITE_HINT_NONE: + case WRITE_HINT_SHORT: + case WRITE_HINT_MEDIUM: + case WRITE_HINT_LONG: + case WRITE_HINT_EXTREME: + inode_set_write_hint(inode, hint); + ret = 0; + break; + default: + ret = -EINVAL; + } + break; + } + default: + ret = -EINVAL; + break; + } + + return ret; +} + static long do_fcntl(int fd, unsigned int cmd, unsigned long arg, struct file *filp) { @@ -337,6 +371,10 @@ static long do_fcntl(int fd, unsigned int cmd, unsigned long arg, case F_GET_SEALS: err = shmem_fcntl(filp, cmd, arg); break; + case F_GET_WRITE_LIFE: + case F_SET_WRITE_LIFE: + err = fcntl_write_life(filp, cmd, arg); + break; default: break; } diff --git a/include/uapi/linux/fcntl.h b/include/uapi/linux/fcntl.h index 813afd6eee71..1c5b2a95e9c9 100644 --- a/include/uapi/linux/fcntl.h +++ b/include/uapi/linux/fcntl.h @@ -43,6 +43,12 @@ /* (1U << 31) is reserved for signed error codes */ /* + * Set/Get write life time hints + */ +#define F_GET_WRITE_LIFE (F_LINUX_SPECIFIC_BASE + 11) +#define F_SET_WRITE_LIFE (F_LINUX_SPECIFIC_BASE + 20) + +/* * Types of directory notifications that may be requested. */ #define DN_ACCESS 0x00000001 /* File accessed */
We have a pwritev2(2) interface based on passing in flags. Add an fcntl interface for querying these flags, and also for setting them as well: F_GET_WRITE_LIFE Returns one of the valid type of write hints, like WRITE_HINT_MEDIUM. F_SET_WRITE_LIFE Pass in a WRITE_HINT_* type to set the write life time hint for this file/inode. Returns 0 on succes, -1 otherwise. Signed-off-by: Jens Axboe <axboe@kernel.dk> --- fs/fcntl.c | 38 ++++++++++++++++++++++++++++++++++++++ include/uapi/linux/fcntl.h | 6 ++++++ 2 files changed, 44 insertions(+)