Btrfs Set To Land Support For IDMAPPED Mounts In Linux 5.15

Written by Michael Larabel in Linux Storage on 12 August 2021 at 06:48 AM EDT. Add A Comment
Introduced to the Linux kernel earlier this year with Linux 5.12 was IDMAPPED mounts that allow for different mounts to expose the same file or directory with different ownership. IDMAPPED mounts was designed with use-cases ranging from containers to systemd-homed and more as outlined in the earlier article. Btrfs is now ready to begin supporting IDMAPPED mounts.

Back when IDMAPPED mounts functionality was added to the Linux kernel, the initial implementation came for FAT and EXT4. XFS support has also been in the works while now for Linux 5.15 the Btrfs support appears ready.

Following a number of patches being queued into the Btrfs kernel development tree, IDMAPPED mounts are now allowed. With various Btrfs changes by Canonical's Christian Brauner, the IDMAPPED mounts support is ready.

With the code now being queued into the Btrfs "for-next" Git code, it makes it material for the upcoming Linux 5.15 merge window.

More details on IDMAPPED mounts functionality can be found via Christian Brauner's FOSDEM 2021 presentation.
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Michael Larabel is the principal author of and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 20,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and automated benchmarking software. He can be followed via Twitter, LinkedIn, or contacted via

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