Bug 430768
| Summary: | opendir / __alloc_dir tries to malloc st_blksize; may fail | ||
|---|---|---|---|
| Product: | [Fedora] Fedora | Reporter: | Eric Sandeen <esandeen> |
| Component: | glibc | Assignee: | Jakub Jelinek <jakub> |
| Status: | CLOSED RAWHIDE | QA Contact: | Fedora Extras Quality Assurance <extras-qa> |
| Severity: | low | Docs Contact: | |
| Priority: | low | ||
| Version: | rawhide | CC: | drepper |
| Target Milestone: | --- | ||
| Target Release: | --- | ||
| Hardware: | All | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | Bug Fix | |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2008-04-10 10:04:59 UTC | Type: | --- |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
And so will many other apps do. Using such huge preferred IO size is not very wise. Agreed, and perhaps even if reporting large IO sizes for files, the fs should report something smaller for directories. But in any case, do you think that glibc (and other apps...) should fall back to smaller sizes if allocation fails? I've checked in upstream a patch to try a possibly smaller allocation if the size provided by st_blksize couldn't be fulfilled. Should be in glibc-2.7.90-14 |
A filesytem may report its preferred IO size (not fundamental block size) in st_blksize, and this might be fairly large: [root@magnesium tmp]# stat mnt File: `mnt' Size: 27 Blocks: 0 IO Block: 536870912 directory Device: 700h/1792d Inode: 128 Links: 3 Access: (0755/drwxr-xr-x) Uid: ( 0/ root) Gid: ( 0/ root) Access: 2008-01-29 11:40:37.091973914 -0600 Modify: 2008-01-29 11:40:50.078976949 -0600 Change: 2008-01-29 11:40:50.078976949 -0600 It appears that opendir / __alloc_dir will attempt to use that size, without fallback: [root@magnesium tmp]# strace -otrace ./test [root@magnesium tmp]# grep -3 53687 trace open("mnt", O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_DIRECTORY|0x80000) = 3 fstat64(3, {st_mode=S_IFDIR|0755, st_size=27, ...}) = 0 fcntl64(3, F_GETFD) = 0x1 (flags FD_CLOEXEC) mmap2(NULL, 536875008, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x97f86000 munmap(0x97f86000, 536875008) = 0 close(3) = 0 exit_group(0) = ? Since st_blksize is "preferred" and the alternative is an opendir failure, should this fall back to smaller sizes on ENOMEM? Thanks, -Eric