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author | rsc <rsc> | 2007-08-27 14:23:48 +0000 |
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committer | rsc <rsc> | 2007-08-27 14:23:48 +0000 |
commit | 6c34f97cb889456c2340a3935d1253f99ec13522 (patch) | |
tree | a2714de705f27a4c0b609cb9c31b02a898be446c | |
parent | a505fd66511db520df12f3fcb83d49b395e4da8a (diff) | |
download | xv6-labs-6c34f97cb889456c2340a3935d1253f99ec13522.tar.gz xv6-labs-6c34f97cb889456c2340a3935d1253f99ec13522.tar.bz2 xv6-labs-6c34f97cb889456c2340a3935d1253f99ec13522.zip |
tell what an inode is
-rw-r--r-- | fs.c | 13 |
1 files changed, 9 insertions, 4 deletions
@@ -98,7 +98,12 @@ bfree(int dev, uint b) brelse(bp); } -// Inodes +// Inodes. +// +// An inode is a single, unnamed file in the file system. +// The inode disk structure holds metadata (the type, device numbers, +// and data size) along with a list of blocks where the associated +// data can be found. // // The inodes are laid out sequentially on disk immediately after // the superblock. The kernel keeps a cache of the in-use @@ -110,9 +115,9 @@ bfree(int dev, uint b) // When ip->ref falls to zero, the inode is no longer cached. // It is an error to use an inode without holding a reference to it. // -// Inodes can be locked with I_BUSY (like bufs and B_BUSY). // Processes are only allowed to read and write inode -// metadata and contents when holding the inode's lock. +// metadata and contents when holding the inode's lock, +// represented by the I_BUSY flag in the in-memory copy. // Because inode locks are held during disk accesses, // they are implemented using a flag rather than with // spin locks. Callers are responsible for locking @@ -123,7 +128,7 @@ bfree(int dev, uint b) // To give maximum control over locking to the callers, // the routines in this file that return inode pointers // return pointers to *unlocked* inodes. It is the callers' -// responsibility to lock them before using them. A non-zero +// responsibility to lock them before using them. A non-zero // ip->ref keeps these unlocked inodes in the cache. struct { |