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c861d71eeb
As pointed out in the comments added in this PR: the in-memory state of the filesystem already has the layer file in its final place. If the fsync fails, but pageserver continues to execute, it's quite easy for subsequent pageserver code to observe the file being there and assume it's durable, when it really isn't. It can happen that we get ENOSPC during the fsync. However, 1. the timeline dir is small (remember, the big layer _file_ has already been synced). Small data means ENOSPC due to delayed allocation races etc are less likely. 2. what else are we going to do in that case? If we decide to bubble up the error, the file remains on disk. We could try to unlink it and fsync after the unlink. If that fails, we would _definitely_ need to error out. Is it worth the trouble though? Side note: all this logic about not carrying on after fsync failure implies that we `sync` the filesystem successfully before we restart the pageserver. We don't do that right now, but should (=> https://github.com/neondatabase/neon/issues/6989) part of https://github.com/neondatabase/neon/issues/6663