mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/kdave/btrfs-progs.git
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50 lines
2.1 KiB
ReStructuredText
50 lines
2.1 KiB
ReStructuredText
maximum file name length
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255
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This limit is imposed by Linux VFS, the structures of BTRFS could store
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larger file names.
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maximum symlink target length
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depends on the *nodesize* value, for 4KiB it's 3949 bytes, for larger nodesize
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it's 4095 due to the system limit PATH_MAX
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The symlink target may not be a valid path, i.e. the path name components
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can exceed the limits (NAME_MAX), there's no content validation at :manref:`symlink(3)`
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creation.
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maximum number of inodes
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2\ :sup:`64` but depends on the available metadata space as the inodes are created
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dynamically
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Each subvolume is an independent namespace of inodes and thus their
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numbers, so the limit is per subvolume, not for the whole filesystem.
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inode numbers
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minimum number: 256 (for subvolumes), regular files and directories: 257,
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maximum number: (2\ :sup:`64` - 256)
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The inode numbers that can be assigned to user created files are from
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the whole 64bit space except first 256 and last 256 in that range that
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are reserved for internal b-tree identifiers.
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maximum file length
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inherent limit of BTRFS is 2\ :sup:`64` (16 EiB) but the practical
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limit of Linux VFS is 2\ :sup:`63` (8 EiB)
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maximum number of subvolumes
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the subvolume ids can go up to 2\ :sup:`48` but the number of actual subvolumes
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depends on the available metadata space
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The space consumed by all subvolume metadata includes bookkeeping of
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shared extents can be large (MiB, GiB). The range is not the full 64bit
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range because of qgroups that use the upper 16 bits for another
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purposes.
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maximum number of hardlinks of a file in a directory
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65536 when the *extref* feature is turned on during mkfs (default), roughly
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100 otherwise and depends on file name length that fits into one metadata node
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minimum filesystem size
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the minimal size of each device depends on the *mixed-bg* feature, without that
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(the default) it's about 109MiB, with mixed-bg it's is 16MiB
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