--- title: EXT4 Lands Optional Buffered IOmap For Significant... description: EXT4 has optional buffered IOmap support, replacing the file-system's buffer head usage with the IOmap framework. The feature requires explicitly enabling the... canonical: https://daily.dev/posts/ext4-lands-optional-buffered-iomap-for-significant-performance-win-with-large-writes-f2qdsbbaw twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: EXT4 Lands Optional Buffered IOmap For Significant Performance Win With Large Writes | daily.dev og:description: EXT4 has optional buffered IOmap support, replacing the file-system's buffer head usage with the IOmap framework. The feature requires explicitly enabling the... og:url: https://daily.dev/posts/ext4-lands-optional-buffered-iomap-for-significant-performance-win-with-large-writes-f2qdsbbaw og:image: https://api.daily.dev/og/posts/F2QDSbBaW.png og:image:alt: EXT4 Lands Optional Buffered IOmap For Significant Performance Win With Large Writes og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # EXT4 Lands Optional Buffered IOmap For Significant Performance Win With Large Writes **[Phoronix](https://daily.dev/sources/phoronix)** · 1 min read · 1 upvotes · 0 comments ## Summary EXT4 has optional buffered IOmap support, replacing the file-system's buffer head usage with the IOmap framework. The feature requires explicitly enabling the new 'buffered_iomap' mount option, since it's not enabled by default. Large writes show significant performance improvements, while read performance is more modest. The mode doesn't support online defragmentation, inline data, fsverify, fscrypt, non-extent inodes, or data=journal mode, and ext4 falls back to the original I/O path automatically when necessary. Zhang Yi of Huawei led the work on buffered IOmap support, and the pull request also includes miscellaneous bug fixes and improvements, including for fast commit and avoiding deadlocks and out-of-bound reads in corner cases involving corrupted file systems. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### What does the buffered_iomap mount option do in EXT4? It enables an alternative buffered I/O code path in EXT4 that replaces the traditional buffer head usage with the IOmap framework, giving significant performance improvements for large writes and more modest gains for reads. It's not enabled by default and must be explicitly set as a mount option. It automatically falls back to the original I/O path when necessary. _Tracking kernel storage changes like this helps before you tune file-system mount options, something daily.dev readers follow closely._ ### What features are unsupported when using EXT4 buffered_iomap mode? Buffered_iomap mode in EXT4 does not support online defragmentation, inline data, fsverity, fscrypt, non-extent inodes, or data=journal mode. If any of these are needed, ext4 falls back automatically to the original I/O code path. This tradeoff was noted in the kernel pull request by Ted Ts'o for Linux 7.4. _Weighing file-system feature tradeoffs before a kernel upgrade is easier when daily.dev surfaces changes like this._ ### Who led development of EXT4's buffered IOmap support? Zhang Yi of Huawei led the work on EXT4's buffered IOmap support, which was merged into the Linux 7.4 kernel alongside fast commit fixes and corrections for deadlocks and out-of-bound reads when handling corrupted file systems. _Keeping up with who drives kernel file-system work is simpler when daily.dev tracks these contributions for you._ ## Similar posts on daily.dev - [IOmap Improvement For Linux 7.3 Takes EXT4 & XFS Performance Further](https://daily.dev/posts/iomap-improvement-for-linux-7-3-takes-ext4-xfs-performance-further-ayzsohqii) · Phoronix · 0 upvotes · 0 comments - [EXT4 Preps More Performance Improvements For Linux 7.3](https://daily.dev/posts/ext4-preps-more-performance-improvements-for-linux-7-3-xhnbgosyd) · Phoronix · 0 upvotes · 0 comments - [Linux 7.2 Optimization Shows \+5% IOPS For EXT4 & XFS After Moving Around Two Lines Of Code](https://daily.dev/posts/linux-7-2-optimization-shows-5-iops-for-ext4-xfs-after-moving-around-two-lines-of-code-nx631vsmn) · Phoronix · 1 upvotes · 0 comments - [Someone moved three lines of code in Linux 7.2 and got a 5% storage speed boost](https://daily.dev/posts/someone-moved-three-lines-of-code-in-linux-7-2-and-got-a-5-storage-speed-boost-4juxmldkx) · XDA Developers · 0 upvotes · 0 comments - [EXT4 In Linux 7.0 Improves Write Performance For Concurrent Direct I/O Writes](https://daily.dev/posts/ext4-in-linux-7-0-improves-write-performance-for-concurrent-direct-i-o-writes-z5kk6zl4o) · Phoronix · 0 upvotes · 0 comments --- Tags: [#linux](https://daily.dev/tags/linux), [#performance](https://daily.dev/tags/performance), [#filesystems](https://daily.dev/tags/filesystems) [View this post on daily.dev](https://daily.dev/posts/ext4-lands-optional-buffered-iomap-for-significant-performance-win-with-large-writes-f2qdsbbaw) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"EXT4 Lands Optional Buffered IOmap For Significant Performance Win With Large Writes","url":"https://daily.dev/posts/ext4-lands-optional-buffered-iomap-for-significant-performance-win-with-large-writes-f2qdsbbaw","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/ext4-lands-optional-buffered-iomap-for-significant-performance-win-with-large-writes-f2qdsbbaw"},"datePublished":"2026-10-26T10:04:10.912Z","dateModified":"2026-10-26T10:15:15.974Z","description":"EXT4 has optional buffered IOmap support, replacing the file-system's buffer head usage with the IOmap framework. 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