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Wong" Cc: brauner@kernel.org, hch@lst.de, jack@suse.cz, cem@kernel.org, kbusch@kernel.org, axboe@kernel.dk, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, gost.dev@samsung.com, linux-api@vger.kernel.org Content-Language: en-US From: Kanchan Joshi In-Reply-To: <20260309163325.GE6033@frogsfrogsfrogs> Content-Transfer-Encoding: 7bit X-CMS-MailID: 20260310175527epcas5p4b20cd0d70a4401b7b213d97540aa43c6 X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" CMS-TYPE: 105P cpgsPolicy: CPGSC10-542,Y X-CFilter-Loop: Reflected X-CMS-RootMailID: 20260309053427epcas5p23419afbe49e4e35526388601e162ee94 References: <20260309052944.156054-1-joshi.k@samsung.com> <20260309052944.156054-2-joshi.k@samsung.com> <20260309163325.GE6033@frogsfrogsfrogs> On 3/9/2026 10:03 PM, Darrick J. Wong wrote: >> +struct fs_write_stream { >> + __u32 op_flags; /* IN: operation flags */ >> + __u32 stream_id; /* IN/OUT: stream value to assign/guery */ >> + __u32 max_streams; /* OUT: max streams values supported */ >> + __u32 rsvd; >> +}; > This isn't an very cohesive interface -- GET_MAX probably only needs > op_flags and max_streams, right? And GET/SET only use op_flags and > stream_id, right? Yeah, right. That's the trade-off with swiss army knife type ioctl which uses op_flags to decide what it should do. Apart from keeping a single ioctl I was thinking a bit about extensibility (for anything new we may be able to do a new op_flags with some rsvd or union) too. But if you feel strong about this, I can take 3 ioctl route? >> +#define FS_WRITE_STREAM_OP_GET_MAX (1 << 0) >> +#define FS_WRITE_STREAM_OP_GET (1 << 1) >> +#define FS_WRITE_STREAM_OP_SET (1 << 2) >> + >> +#define FS_IOC_WRITE_STREAM _IOWR('f', 43, struct fs_write_stream) > EXT4_IOC_CHECKPOINT already took 'f' / 43. I/think/ there's no problem > because its argument is a u32 and ioctl definitions incorporate the > lower bits of of the argument size but you might want to be careful > anyway. Indeed, thanks!